
ass. 



Book. 



^C74- 



Copyright N 



JO 



copyright ul:fosit. 




Exposed places of main arteries. 



( Seepages 314 and 315.) 



PHYSIOLOGY 

PRACTICAL AND DESCRIPTIVE 



BY 



BUEL P. COLTON, A.M. 

I\ 

PROFESSOR OF BIOLOGICAL SCIENCES 

ILLINOIS STATE NORMAL UNIVERSITY 

AUTHOR OF 

"PHYSIOLOGY, EXPERIMENTAL AND DESCRIPTIVE" 

" ELEMENTARY PHYSIOLOGY AND HYGIENE " 

"PRACTICAL PHYSIOLOGY" 

"ZOOLOGY, DESCRIPTIVE AND PRACTICAL" 

"TEACHER'S MANUAL OF ZOOLOGY" 

" PRACTICAL ZOOLOGY " 



PART I — DESCRIPTIVE 



" "What a piece of work is a man ! how noble in reason ! 
how infinite in faculty ! in form and moving, how express 
and admirable ! in action, how like an angel ! in appre- 
hension, how like a god ! the beauty of the world ! the 
paragon of animals ! " 



BOSTON, U.S.A. 

D. C. HEATH & CO., PUBLISHERS 

1906 



6 



uunuiiuo 



Twe Cooies Received 

JUN 6 1906 

f\ Couyrieht Entry 



"+%$#'* 



c 74 



COLTON'S PHYSIOLOGIES 



PHYSIOLOGY : Experimental and Descriptive . . . $1.12 

For Normal Schools and Colleges. 440 pages. Illus- 
trated in colors. 

PHYSIOLOGY: Briefer Course 90 

For High Schools. 399 pages. Illustrated in colors. 



PRACTICAL PHYSIOLOGY 

Laboratory Work in Physiology. 168 pages. Illustrated. 

PHYSIOLOGY : Practical and Descriptive 

This consists of the Briefer Course and the Practical Physi- 
ology bound in one volume. ' 

ELEMENTARY PHYSIOLOGY AND HYGIENE . 

For Grammar Schools. 320 pages. Illustrated. 

GOOD HEALTH FOR GIRLS AND BOYS . 

An Introduction to the Elementary Physiology, for Inter- 
mediate Grades, by Bertha M. Brown. 164 pages. 
Illustrated. 



.60 



1.40 



.60 



•45 



D. C. HEATH & CO., Publishers, Boston, New York, Chicago 



Prac. and Des. 



Copyright, 1899, 1901, and 1906, 
By BUEL P. COLTON. 



PREFACE 



The author's " Experimental and Descriptive Physiol- 
ogy" has been adopted by a large number of schools and 
colleges. But there are many schools in which, owing to 
the youth of the pupils, the shortness of the time allotted to 
the subject, or the meagerness of laboratory facilities, such 
a rigorous course cannot be taken. For such schools this 
simpler book is written. While it contains considerably 
less experiment and dissection than the larger book, it is 
still based upon experimental work. No teaching of physi- 
ology is worthy of the name unless it rests upon experi- 
ment, observation, and dissection. The ridiculous answers 
of the pupil who has learned mere "book physiology" 
furnish the standard jest of the educational journal. Try- 
ing to teach physiology without experiment is not only in 
opposition to modern views of pedagogy and psychology, 
but it is equally at variance with the common sense of the 
business man's view. Such teaching is a mere mummery 
of words — it teaches neither how to know nor to do. 

In fitting this work for the less mature mind, special 
attention has been paid to conciseness and brevity of state- 
ment and to clearness of exposition. Sentences and para- 

iii 



iv PREFACE. 

graphs have been made short; chapters are short, with 
definite summaries appended. 

Function, rather than structure, has been made promi- 
nent. Only so much of anatomy as is really needed to 
understand the working of the organs has been introduced. 
The experimental work and directions for dissection, as 
well as some of the more difficult points, have been put in 
smaller type, so they may more readily be omitted where 
it is not possible to complete all the work in the given 
time. 

Although hygiene has been given a prominent place, 
yet it may be claimed that when the pupil is well grounded 
in the functions of the different organs, from observational 
and experimental work, many of the rules of hygiene will 
readily occur to him as natural inferences. When other 
rules for the preservation of health, which might not occur 
to him, are suggested, he will see their significance because 
he understands the underlying principle ; and he not only 
can, but will, obey the rule better because he sees reason 
in it, and does not follow it blindly as an arbitrary law 
thrust upon him. Questions are given, at the end of each 
chapter, to test the pupil's knowledge of principles by 
application to new cases. 

Some of the more desirable reforms in nomenclature have 
been adopted ; among these are the use of the terms ante- 
rior, meaning toward the head ; posterior, in the opposite 
direction ; dorsal, toward the back ; ventral, toward the 
region of the belly. These terms, used instead of " up " 



PREFACE, V 

and "down," "front" and "back," will do away with 
much confusion, especially since we are obliged to use the 
structure of horizontal-bodied animals to illustrate human 
anatomy. Many Latin terms, such as "vena cava" should 
be replaced by English, as caval vein. Postcaval vein and 
precaval vein are easier and better than " vena cava infe- 
rior" and "vena cava superior." In many cases the 
English plural may well replace the Greek or Latin form, 
as ganglion, plural ganglions. Blood tube is better than 
"bloodvessel." The best authorities say spinal bulb in- 
stead of the long "medulla oblongata." Food tube is 
simpler than " alimentary canal," especially as the tube is 
not canal-like. The rib-bearing vertebras are thoracic, and 
are no more " dorsal " than the other parts of the spinal 
column. 

Effort has been made to lay stress on the more impor- 
tant topics, and the skeleton is relegated to a subsidiary 
place, as a knowledge of it has so little to do with practical 
hygiene. The heart and the stomach receive full treat- 
ment, while matters of such slight importance as the hair 
and nails are briefly dismissed. 

The order of topics is the result of long experience. 
For many years the author has sought to find the most 
natural sequence of subjects, so that, as the work pro- 
gressed, the pupil would find the way .best prepared for 
him. Without claiming that this is the best sequence, the 
writer is sure that it is the "path of least resistance." 

The subject of Alcohol has-been treated in full com- 



vi PREFACE. 

pliance with the law. Copious quotations have been taken 
from the best authorities on this subject. The same 
high-grade illustrations have been used that brought such 
favorable comment on the earlier work. 

This briefer edition has, too, the full benefit of the 
criticism of the eminent authorities whose names are listed 
in the larger work. 

TO THE TEACHER. 

For any practical work in physiology it is very desirable 
to have a room furnished with tables and supplied with 
water. 

Each pupil should make full notes and drawings of the 
work done and the organs studied and dissected. Only by 
so doing will he firmly fix and retain what he gathers from 
day to day. 

In the Practical Physiology are many experiments and 
dissections given in full which are here omitted in order to 
present a briefer course. In the same work there is also 
given a list of books which are most helpful in teaching 
physiology. 



CONTENTS. 



CHAPTER I. 

PAGE 

Introduction i 

Health. Care of the Body. Hygiene. Physiology. Organ. Func- 
tion. Anatomy. Tissues. Cells. Physiological Division of Labor. 

CHAPTER II. 
Motion 7 

Motion Necessary to Life. Experiments with our Muscles. Action 
of Muscle. Structure of Muscle. Connective Tissue. Laws of 
Muscle Action. Flexors and Extensors. Symmetry. Muscles and 
Bones. Levers. Locomotion. Uses of Bones. 

CHAPTER III. 

The General Functions of the Nervous System — Sensation 

and Motion 24 

Muscles controlled by Nerves. Voluntary and Involuntary Motion. 
The Spinal Cord. The Spinal Nerves. Structure of Nerves. 
Function of Nerves. Structure of the Spinal Cord. Ganglions. 
Reflex Action of the Spinal Cord. Reflex Action of the Spinal 
Cord in the Frog. Function of the Nerve Roots. Importance of 
Reflex Action. Inhibition. Nature of a Nervous Impulse. Har- 
mony in Muscle Action. Nerves depend on Blood Supply. 

CHAPTER IV. 

Circulation of the Blood 39 

The Blood and its Work. The Rate of the Heart Beat. Position 
and Size of the Heart. The Valves of the Heart. The Blood 
Tubes Connected with the Heart. The Action of the Heart. Work 
and Rest of the Heart. Action of the Large Arteries. Variation 
in Blood Supply. Plain Muscle Fibers in the Walls of the Arteries. 



viii CONTENTS. 

PAGE 

Circulation of Blood in the Web of the Frog's Foot. Blood Flow in 
the Capillaries. The Veins. The Valves in the Veins. Effect of 
Pressure on the Veins. Rate of Blood Flow. Nourishment of the 
Walls of the Heart. Effect of Gravity on Circulation. 

CHAPTER V. 
Control of Circulation. — The Blood and the Lymph .... 64 
The Effect of Emotions on Circulation. Rhythmic Action of the 
Heart. Nerve Control of the Heart. Sympathetic Nervous System. 
The Vagus Nerve. Inhibition. Vaso-motor Nerves. Blushing. 
Regulation of the Size of the Arteries. Effect of Exercise on the 
Size of the Arteries. Effects of Alcohol on Circulation. The 
Blood. The Corpuscles of the Blood. The Plasma. Hemoglobin. 
Coagulation of Blood. Fibrin. Amount of Blood. Distribution of 
Blood. The Lymph Spaces. Lymph Tubes. Lymphatic Glands. 
Flow of Lymph. Massage. Transfusion of Blood. 

CHAPTER VI. 
Respiration 84 

The Close Relation between Circulation and Respiration. Organs 
of Respiration. Structure of the Lungs. The Windpipe. Cilia. 
The Pleura. The Diaphragm. Action of the Diaphragm. Move- 
ments of Respiration. Forces of Inspiration. Resistances to Inspi- 
ration. Elastic Reactions of Expiration. Forced Respiration. Rate 
of Respiration. Modifications of Respiration. Lung Capacity. 
Hygiene of Respiration. Breathing through the Mouth. Control 
of Respiration. Chemistry of Respiration. Composition of the 
Air. Exchanges between the Air and the Blood in the Lungs. 
Oxyhemoglobin. The Gases in the Blood. Production of Heat 
and Motion in the Body. Oxidation of Live Tissues. Body and 
Locomotive Compared. Storage of Oxygen in the Tissues. Re- 
breathing Air. 

CHAPTER VII. 
Ventilation and Heating. — Dust and Bacteria 1 14 

Need of Ventilation. Grates. Principles of Ventilation. Stoves. 
Furnaces. Foul-air Shafts and Fans. Steam and Hot-water 
Heating. Direct and Indirect Heating. Dead Dust. Sources of 
Dust. Live Dust. Consumption. Disease Germs. Bacteria. How 
to avoid Dust. Sweeping. Contagious Diseases. Putrefaction. 
Preservation of Foods. Need of Removal of Waste. 



CONTENTS. ix 

CHAPTER VIII. 

PAGE 

Excretion 130 

The Skin throws off Perspiration. The Structure of the Skin. The 
Epidermis. Color of the Skin. The Dermis. Sweat Glands. Es- 
sentials of a Gland. Blood Supply of Glands. Oil Glands. 
Composition of Sweat. Amount of Perspiration. Functions of the 
Skin. Regulation of Bodily Temperature by the Skin. Distribu- 
tion of Heat in the Body. Regulation of Bodily Temperature by 
Food and Clothing. The Kidneys. Work of the Kidneys. Rela- 
tion of the Skin and Kidneys. 

CHAPTER IX. 
Foods and Cooking 144 

Necessity of Food. Food Defined. Foodstuffs. Proteids. Impor- 
tance of Proteids. Meat. Fish. Eggs. Milk. Cheese. Vege- 
table Proteids. Carbohydrates. Grains. Wheat. Corn. Rice. 
Oats. Potatoes. Vegetables. Fruits. Water. Impurities in 
Water. Typhoid Fever. Ice-water. Boiling Water. Salts. 
Necessity of a Mixed Diet. Effects of Cold on Appetite for Fats. 
Vegetarians. Tea. Coffee. Beef Tea. Cooking. Soups. 

CHAPTER X. 
The Digestive System 159 

The Object of Food. The Digestive Tube. Organs of Digestion. 
The Mouth. The Teeth — Kinds, Structure, Arrangement. Care 
of the Teeth. Salivary Glands. Action of Salivary Glands. Saliva 
and its Uses. Mucus and Mucous Glands. The Pharynx. Swal- 
lowing. The Gullet. The Structure of the Stomach. Gastric 
Glands. Blood Supply of the Stomach. Stomach Digestion. 
Churning Action of the Stomach. Time of Stomach Digestion. 
Chyme. Absorption from the Stomach. The Intestine. The 
Liver. The Pancreas. Bile. Pancreatic Juice. The Portal Circu- 
lation. Functions of the Bile. Work of the Pancreatic Juice. 
Intestinal Juice. 

CHAPTER XT 
Absorption — Digestion Completed. 181 

Absorption. Villi. Routes of Different Foods after Absorption. Dif- 
fusion and Osmosis. Absorption a Vital Process. The Lacteals 
and the Lymphatics. Outline of Digestion. The Colon. Work 
of the Large Intestine. Constipation. Laxative and Constipating 



[ 95 



X CONTENTS. 

Foods. Hygiene of Digestion. Deliberation in Eating. Thorough 
Mastication. Effects of Repose on Digestion. Conversation at 
Meals. Value of Soups and Desserts. Hot Drink at Meals. Time 
of Meals. Eating between Meals. Amount of Food Needed. 
Errors in Diet. 

CHAPTER XII. 

Nutrition : 

Ledger Account of the Body and its Organs. Blood a Mixture of 
Good and Bad. Action of Diseased Kidneys. Blood Stream like 
Water Pipes and Sewer Combined. A Living Eddy. Importance 
of Renewal of Blood and Lymph. Fat as a Tissue. Hibernation. 
Respiration and Oxidation of Candle. Glycogen. Muscular Exer- 
tion and Excretion of Urea. Metabolism. Indestructibility of 
Matter. Indestructibility of Force. Utilization of Energy in the 
Body and in Machines. Correlation and Conservation of Energy. 

CHAPTER XIII. 
Alcohol 208 

Fermentation. Yeast. Wines. Danger in Wine Drinking. Cider. 
"Temperance Drinks." Malt and Distilled Liquors. Physical and 
Chemical Properties of Alcohol. Physiological Effects. Formerly 
regarded as a Stimulant. A Narcotic. Is Alcohol a Food ? The 
Danger of Moderate Use. Alcohol as a Poisonous Drug. 

CHAPTER XIV. 
Exercise and Bathing 226 

How Exercise is Beneficial. Exercise for General Health. Nature's 
Rewards and Punishments. Exercise prolongs Life. Choice of 
Exercise. Games of School Children. Tennis. Baseball and 
Football. Boxing. Bicycling. Exercise for Middle-aged Men. 
Taking Cold. Diarrhea. Bathing. Cold Baths. Bath Mits. Time 
for Bathing. Warm Baths vs. Cold Baths. Exercise Arterial Mus- 
cles. Habit of Cold Bathing acquired gradually. 

CHAPTER XV. 
The Brain 235 

The Coverings of the Brain. Parts of the Brain. The Cerebrum. 
The Cerebellum. The Spinal Bulb. Brain of a Cat or Rabbit. 
Cranial Nerves and their Functions. Hemispheres of the Cerebrum. 
Brain Convolutions and Intelligence. Gray and White Matter of 
the Brain. Neuroglia. Functions of the Cerebrum. Pigeon 
with Cerebrum Removed. Functions of Cerebral Cortex. Center 



CONTENTS. XI 

PAGE 

of Sensations itself Insensible. Crossed Control of the Body. Lo- 
cation of Brain Functions. Left Hemisphere better Developed. 
Location of Sensation Centers. Brain Work and Brain Rest. 
Sleeplessness. Fatigue. Control of Mind. Habit of Resting the 
Brain. Nervous Tissues least Affected by Starvation. Blood Supply 
of the Brain. Fainting. Apoplexy. Meningitis. The Water 
Cushion of the Brain. Relative Activity of Gray and White Matter. 

CHAPTER XVI. 

Effects of Alcohol on the Nervous System 250 

Effects of Alcohol on Nervous Tissue. Effects of Small Doses on 
Mental Operations. Effects of Continued Use. Moral Deterioration 
produced by Alcohol. Narcotics. Opium. Cocaine. Chloral Hy- 
drate. Chloroform. Tobacco. Cigarette Smoking. 

CHAPTER XVII. 

General Considerations concerning the Nervous System . . . 261 
Nerve Stimuli. Kinds of Nerve Stimuli. Essential Similarity of All 
Nerve Fibers. Relation of Stimulus and Sensation. Reaction 
Time. Reflex Action. Connection of Brain Centers. Nature of 
Sensation. Subjective Sensations. The Relative Nature of Sensa- 
tion. Induction Currents used in Physiological Experiments. 
Dreams. Lingering Effect of Sensations. Habits are Acquired 
Reflex Actions. Usefulness of Resting. Nervous System vs. Tele- 
graph System. Efferent Currents. Afferent Currents. 

CHAPTER XVIII. 
The General Senses 271 

The Body a Collection of Organs. Influence from the External World. 
Classification of the Senses. General Sensations and Special Senses. 
The Muscular Sense. Importance of Muscular Sense. Dependence 
of Sight on Muscular Sense and Touch. Pain. Pain a General 
Sense. Extent of Pain. Use of Pain. Hunger and Thirst. 

CHAPTER XIX. 
The Special Senses — Touch and Temperature Sense .... 278 
What we learn by Touching Objects. Cutaneous Sensations. Nerve 
Endings in the Skin. Touch Corpuscles. Touch the most General 
of the Senses. Pressure Sense. Local Sign. Test by Compass 
Points. Reference of Sensation to the Region of the Nerve End- 
ings. Temperature Sense. 



xii CONTENTS. 

CHAPTER XX. 

PAGE 

The Sense of Sight 285 

Protection of the Eye. The Lacrymal Secretion. External Parts of 
the Eye. The Conjunctiva. Muscles of the Eyeball. Movements 
of the Eye. Coats of the Eye. The Sclerotic Coat. The Choroid 
Coat. The Retina. The Cornea. The Iris. The Pupil. Regula- 
tion of the Amount of Light admitted into the Eye. The Refract- 
ing Media of the Eye. The Aqueous Humor. The Vitreous Humor. 
The Crystalline Lens. The Lens Capsule. The Hyaloid Mem- 
brane. The Ciliary Muscle. Inversion of the Image. Adjustment 
for Distance. Action of the Ciliary Muscle. Defects of Eyesight. 
Structure of the Retina. Importance of the Retina. The Blind 
Spot. The Optic Nerve not Sensitive to Light. Sympathy between 
the Eyes. Pain in the Eyes. Color Sensations. Color Blindness. 
Stereoscopic Vision. After-images. Care of the Eyes. 

CHAPTER XXI. 

Taste, Smell, and Hearing 301 

Uses of the Sense of Taste. The Papillae. Nerve Supply of the 
Tongue. Solution Necessary for Tasting. Flavors. Effect of 
Temperature on Taste. The Sense of Smell. Why we Sniff. The 
Sense of Hearing. The External Ear. The Tympanum. The 
Middle Ear. The Eustachian Tube. The Internal Ear. The Pro- 
duction of Sound. The Equilibrium Sense. The Care of the Ear. 
The Use of the Ears. 

CHAPTER XXII. 
The Voice 309 

The Ear and the Voice. What we can learn from our own Throats. 
The Vocal Cords. Reenforcement of Sound. Pitch and Voice. 
Voice and Speech. Vowels and Consonants. Difference between 
Voices. Hoarseness. Whispering. Culture of the Voice. 

CHAPTER XXIII. 

Accidents. — What to do till the Doctor Comes 314 

How to stop Flow of Blood from Arteries. Bleeding from the Upper 
Arm. Bleeding from the Neck. Wounds in the Thigh. Bleeding 
from Veins. Hemorrhage of the Lungs or Stomach. Bleeding from 
the Nose. Treatment of Burns. Danger from Burning Clothing. 



CONTENTS. xiii 

PAGE 

Treatment of Fainting. Broken Bones. Sunstroke. Treatment of 
the Drowned. Swimming. Suffocation in Wells. Bites of Cats, 
Dogs, etc. Wounds from Thorns, Rusty Nails, etc. Snake Bites. 
Poisons and their Antidotes. Poison Ivy. The Sick-room. Qual- 
ities of the Nurse. Care of the Sick. 

CHAPTER XXIV. 

The Skeleton 330 

Axial Skeleton. Appendicular Skeleton. Uses of the Bones. Study 
of a Vertebra. Table of the Bones. The Spinal Column. Articu- 
lations of a Vertebra. The Cervical Vertebras. Atlas and Axis. 
The Thoracic Vertebras. The Lumbar Vertebras. The Sacrum and 
the Coccyx. Flexibility of the Spinal Column. Curves of the Spinal 
Column. Cavities of the Skeleton. Pronation and Supination. 
Weight of the Bones. Microscopic Structure of Bone. Classifica- 
tion of Joints. Sprains and Dislocations. 

CHAPTER XXV. 
The Muscles 341 

The Number of Muscles. The Arrangement of Muscles. Forms of 
Muscles. Names of Muscles. Peculiar Muscles. Heart Muscle. 
Three kinds of Muscular Fiber Compared. Each Fiber a Cell. 
Muscles of Expression. Muscles and Fat. Convulsions. Rigor 
Mortis. Some Prominent Muscles. Sculpture and Anatomy. 



Appendix 347 

Antidotes. Disinfectants. Vital Statistics. 

Glossary 360 

Index 371 



PHYSIOLOGY: PRACTICAL 
AND DESCRIPTIVE. 

PART I. — DESCRIPTIVE. 



CHAPTER I. 
INTRODUCTION. 

Health. — Is it not a splendid thing to be well and 
strong ? To be full of bounding health ? To " feel one's 
life in every limb " ? 

Who does not desire to prolong, so far as possible, this 
condition characteristic of youth ? 

Natural and Artificial Modes of Life. — An animal 
living in a state of nature may keep well and live its 
natural period of life without knowing anything about the 
laws of health. But as students or indoor workers, many 
of us lead a sedentary life ; we are not natural, but often 
highly artificial, in our mode of living. We move about 
but little, whereas the animal abounds in motion. We 
concentrate energy upon mental effort, thus diverting a 
large share of our sum total of energy away from the pro- 
cess of nutrition. We often shut ourselves in rooms nearly 
air-tight. We eat poorly chosen and ill-prepared food. 
We devour it hastily, often when we are not in fit con- 
dition to take food. In short, we frequently disobey the 
laws of Nature. Now, Nature punishes every violation of 
her laws. She never forgives, never forgets. 

1 



2 PHYSIOLOGY. 

Value of Knowledge. — The out-of-door worker may 
not suffer so much from ignorance in these matters. 
From the character of his occupation, he is, to a certain 
extent, obliged to obey Nature. He gets enough fresh 
air. His bodily exertion generally brings a hearty appe- 
tite, vigorous digestion, active circulation of the blood. 
Still, he would greatly profit by knowing something of the 
nature of his food, its wholesomeness or unwholesomeness. 
The fact that he has fair health is no proof that he always 
does the best thing. His natural mode of life may keep 
him in tolerably good condition in spite of his violation of 
certain laws; but he could undoubtedly learn how to 
economize in the purchase, preparation, and proper com- 
bination of foods. 

Importance of the Care of the Body. — Any machine 
of man's invention must be kept in good running order if 
we would have it do good work, or last long. We must 
keep a machine clean, well oiled, and not overtax it. Are 
not our bodies worth equal care ? If some part of a ma- 
chine is broken, we may replace it at moderate expense ; 
but none of the vital organs can be replaced. We may 
get a new mainspring for a watch, but we cannot obtain a 
new stomach or lungs. 

Its Admirable Mechanism. — Aside from the above 
considerations the human body is worthy of study for its 
own sake. Viewed simply as a mechanism, it is wonder- 
ful. Each organ is so well adapted to its work, and all 
the organs work so harmoniously through their connection 
and control by the nervous system, that we never cease to 
admire it. We admire a doll, or other toy, so ingeniously 
constructed that it can move its eyes or walk a short time 
after being wound up. But this live mechanism, which is 



INTRODUCTION'. 3 

self-winding, self -regulating, self-repairing, self -directing, 
amazes us. 

Hygiene. — We take up the study of the human body 
mainly that we may learn how to preserve health ; the 
science of health is hygiene. 

Physiology. — In order to keep the various organs in 
good order we must know what their natural work is, and 
how they do it ; the science of the action of the body and 
its parts is physiology. 

Organ. — Any part, or member, of the body, which has 
a special work to do, is called an organ, as the hand, the 
eye, or the stomach. 

Function. — The work, or action, of each organ is 
its function. 

Anatomy. — In order to understand the working of 
each organ it is usually necessary to know something 
of its construction ; the science of structure is anatomy. 
We do not need to go far into anatomy to obtain a fair 
knowledge of the manner in which our organs do their 
work. The surgeon, of course, must be able to locate 
accurately the various blood tubes, nerves, muscles, etc. 
We need to know only the general structure of the body 
and, more in detail, some of the more important organs, 
such as the heart, the lungs, the larynx, the eye, etc. 
It is fortunate for us that these organs in the sheep, pig, 
and cow are so nearly like our own that they serve 
admirably to enable us to understand ourselves. 

Tissues. — Every organ is composed of several different 
kinds of material. For instance, in a slice across a ham 
we see the skin on the outside, then fat, lean, and bone. 



4 PHYSIOLOGY. 

These " primary building materials " of the body we call 
tissues. A tissue may be defined as an aggregation of 
similar cells devoted to a common work. 

Cells. — The whole body is made up of small parts 
called cells, comparable to the bricks in a house. These 
cells are of various shapes in the different tissues. 

In the more active tissues the cells are alive, and each 
cell may be compared to the ameba, a little mass of living 
jelly-like substance called protoplasm. The ameba is a 
protozoan often found in slime at the bottom of stagnant 
water. Within this is a small, rounded part called the 
nucleus. Most of the cells of the body differ from 
the ameba in having a distinct 
outer covering or cell wall. A grape 
serves very well to show what a cell 
is like. The whole body is built up 
Nucleus . of cells, few of them large enough 

Fig. 1. Epithelial ceils from to be seen by the naked eye. 
the mside of the cheek. Although the cells are closely 

packed together, each cell leads, in one sense, an inde- 
pendent life. But all work together to maintain the life 
of the body. The cell is like the individual in a com- 
munity. Each lives primarily for itself, yet all work 
together for the good of the whole. 

Epithelial Cells from the Inside of the Cheek. — With the blade of 
a very dull knife, or the handle of a scalpel, gently scrape the inside of 
the cheek. Place a little of the white scraping on a slide in a drop 
of water, cover with a cover slip, and examine under a quarter-inch 
objective. Many cells will be seen, some of them showing nuclei. 
Compare these cells with the accompanying figure. 

The Physiological Division of Labor. — We are aware 
of the advantages of division of labor in a community. If 




INTRODUCTION. 5 

each person learns to do one thing well, all together work 
economically for the common good, time is saved, and 
better goods are produced. In the body there is a division 
of labor similar to that of a community. Each organ has 
its own work to do, and all work together for the common 
welfare. The cells of each tissue have certain properties 
and peculiarities of form differing from the form and 
properties of the cells of any other tissue. While the 
general structure of all cells is essentially the same, and 
while they all have certain properties in common, each has 
some one kind of work that it can do well, and to which 
work it devotes itself. The nerve cells receive impressions 
from the outer world, carry nervous impulses, and control 
the various activities of the body. The muscle cells have 
as their work the production of motion. All the cells 
must take food for themselves and grow. Each has a 
birth, life, and death, as each individual in a community 
of men ; and as the community endures, while the indi- 
vidual members are continually changing, so, in the body, 
while the form remains about the same from year to year, 
the cells are continually changing, some dying, and others 
taking their places. 

In an animal of a single cell, like the ameba, the one 
cell must do everything for itself. The higher animals all 
begin their individual life as an egg, which is, in fact, a 
single minute cell. This grows and divides, forming two 
cells. By repeated division there accumulates a mass 
of cells. These take on the arrangement peculiar to the 
kind of animal from which the egg came. But as the cells 
increase in number one group of cells takes up one part 
of the work of the body, other cells another part of the 
work, and so on. 

In studying history (sociology) we have to deal with the 



6 PHYSIOLOGY. 

individual, the community, the state, and the nation. The 
cell is an individual, the community is a tissue, the state is 
an organ, and the nation is one body. 

Let us proceed to study the nature of the individual cell, 
and the combined actions of these individuals in that com- 
munity called the human body. 



Summary. — I. Health is essential to comfort and efficiency in 
work. 

2. Our artificial mode of life is at variance with nature's laws. 

3. Only by obeying the laws of nature can we preserve health. 

4. We should learn these laws of nature from the advice and ex- 
perience of others, and not by the expensive process of suffering from 
disobedience. 

5. Anatomy is the science of structure. Human anatomy is the 
science of the structure of the human body. 

6. Physiology is the science of function. 

7. Hygiene is the art of preserving health. 

8. Cells are the units of structure in the body. 

9. A tissue is a group of similar cells having a single function. 

10. An organ is a part having a special work or function. The 
organs work together for the common good of the whole organism. 
This working together results in — 

1 1 . The physiological division of labor, in which each organ works 
for all the others, and is dependent on all the other organs. 

Questions. — 1. What are some of the ways in which we most fre- 
quently violate the laws of health ? 

2. Name the more important organs of the body and their functions. 

3. Name the different tissues of one of these organs. 



CHAPTER II. 
MOTION. 

Motion and Life. — Motion is the most manifest sign of 
life. While we are sitting still, as we say, there are fre- 
quent slight motions of the head, body, and limbs. Even 
during sleep the movements of breathing may be seen ; 
the hand laid upon the chest may feel the beating of the 
heart, and the finger detect the pulse in a number of 
places. 

We must move to get our food, or at least to eat and 
digest it. Motion is necessary for breathing, for circu- 
lating the blood, for getting rid of wastes. We often move 
to avoid injury. 

Motion is necessary for seeing : we must turn the face 
toward the object ; we move the eyeballs ; within the eye 
are motions to regulate the amount of light admitted, and 
to adapt the eye for seeing at different distances. 

In feeling, we put forth the hand to touch the object. 
In tasting, we touch the tongue to the object. In smelling, 
we sniff ; and sniffing is a respiratory motion. In hearing 
and in speech there is also motion. 

How are all these motions produced ? 

Experiments with the Muscles in our own Bodies. — i. Clasp 
the front of the right upper arm ; draw up the forearm strongly 
and as far as possible. Note what changes are felt in the biceps 
muscle. 

2. Repeat the experiment, and with the thumb and finger feel the 
cord, or tendon, at the lower end of the muscle, just within the angle of 
the elbow. 



8 PHYSIOLOGY. 

3. Place a weight in the hand, and repeat the act, noting the con- 
dition of the muscle during the experiment ; also note the condition 
of the tendon. 

4. Span the muscle, placing the tips of the fingers in the angle of 
the elbow, and the tip of the thumb as far as you can up the arm; again 
bend the arm. What change in the muscle does this show ? Any 
muscle that bends a limb, as does the biceps, is called a flexor muscle. 

5. Clasp the back of the right upper arm; forcibly straighten the 
arm. The muscle lying along the back of the arm is the triceps muscle. 
It is called an extensor muscle because it extends, or straightens, the 
arm. 

6. Clasp the upper side of the right forearm near the elbow; 
clench the right hand quickly and forcibly ; repeat rapidly. 

7. Notice the thick mass of muscle at the base of the thumb; 
pinch the forefinger and thumb strongly together. What changes can 
be seen and felt ? 

8. Place the hand on the outside of the shoulder; raise the arm to 
a horizontal position; repeat with a weight in the hand. 




Fig. 2. The Shortening and Thickening of the Biceps Muscle in raising the 
Forearm. 



9. Stand erect with the heels close to each other, but not quite 
touching; let the arms hang freely by the sides; rise on tiptoes, 
without moving otherwise ; repeat ten times. 

10. Place the tips of the fingers on the angles of the lower jaw; 
shut the teeth firmly on a piece of rubber, and note the bulging of the 
masseter muscles. 



MOTION. 9 

11. Press the fingers on the temples ; again shut the jaw firmly, and 
feel the action of the temporal muscles. 

12. Make a narrow band of paper that will snugly fit the forearm 
when the hand is open ; now clench the fist strongly. 

13. With a tape measure take the circumference of the upper arm 
when the arm hangs free ; again when the forearm is strongly flexed. 

14. In the same way measure the forearm when the hand is open, 
and when the hand is clenched. 

By these experiments we learn that when a muscle works it becomes 
shorter, thicker, and harder. 

Nerves and Muscles of a Rabbit's Leg. — In the hind leg of a 
rabbit the sciatic nerve may be found by separating two large 
muscles on the sides of the thigh, beginning behind the knee joint. 
The shape and connections of the muscles may be learned, and also 
the distribution of the nerve. 

The Action of Muscle. — The action of muscle is always 
a "pull." The muscle shortens, at the same time thick- 
ening and hardening. These changes in muscle are 
roughly shown in the preceding experiments of feeling 
the arm during its action. But the isolated calf muscle of 
the frog may be made to prove the characteristic changes 
with great clearness. 

Action of Frog's Muscle. — A frog may be killed painlessly by put- 
ting a teaspoonful of ether into a fruit jar of water, immersing the frog 
and capping the jar. When the frog becomes motionless, its head 
should be cut off and a wire run down the spinal column to destroy the 
spinal cord. After cutting the skin around the base of one thigh the 
skin may easily be stripped from the whole hind limb. If the muscles 
on the back of the thigh be gently separated there will be found a white 
thread running lengthwise, the sciatic nerve. It should be severed 
near the hip and carefully turned down upon the calf muscle. It should 
not be pinched or dragged. The muscles of the thigh should now all 
be cut away, being careful not to sever the nerve near the knee. The 
hip joint should be unjointed. With the handle of the scalpel the calf 
muscle should be separated from the shin bone, and just below the 
knee the shin bone and all the muscles except the calf muscle severed. 



10 



PHYSIOLOGY. 



If now the heel cord be cut off below the heel there will remain such a 
preparation as is represented in the accompanying figure, consisting of 
the thigh bone with the calf muscle hanging from it, and the sciatic 




SHORTENED 



ELONGATED 

Fig. 3. Action of the Calf Muscle of the Frog, showing the Relations of the 
Sciatic Nerve. 



nerve still connected with the calf muscle. This may be supported by 
holding the end of the thigh bone in a clamp on a retort stand. A 
0ri . light weight should be attached to 

the heel cord. The muscle and 
Bundle of Muscle Fibers nerve should be moistened with 
water containing a little salt. On 
pinching the free end of the nerve, 
or cutting off the least bit with 
scissors, the muscle will be made 
to act. The shortening and thick- 
ening will be plainly seen, and 
by taking it between the thumb 
and finger the hardening may be 
felt. 





Muscle Sheath 

CROSS SECTION 



— Tendon 



Insertion 
LONGITUDINAL SECTION 

The Structure of Muscle. 



Fig. 4. 



Structure of Muscle. — 

Chipped beef shows well 
the structure of muscle. The 



MOTION. 



II 



white network is the connective tissue. In the meshes 
is the red muscular tissue. The partitions which run all 
through the muscle are continuous with the muscle sheath, 
and both are continuous with the tendons at the ends of 
the muscle. In fresh muscle the sheath and the parti- 
tions are nearly transparent, and are not easily seen. 
When the meat is cooked or salted the connective tissue 
becomes white and opaque. 

Microscopic Structure of Muscle. — In frog's or rabbit's muscle 
observe the thin, transparent membrane covering the muscle, the muscle 
sheath. With forceps tear away part of the 
muscle sheath. Tear the muscle to pieces, 
and note its fibrous structure. A shred of 
muscle may be mounted in a drop of nor- 
mal saline solution on a slide, and exam- 
ined with low power of the microscope. If 
examined with a higher power the cross- 
markings, or striations, will be seen. Such 
muscle is called striated or striped muscle. 
All of the muscles used in ordinary motions 
are of this kind. 




Fig. 5. Two Muscular Fibers 
showing the Terminations of 
the Nerves. 



Effects of Cooking Muscle. — In 

well-cooked corned beef the connec- 
tive tissue is thoroughly softened, 

and the muscle fibers are easily separated. Thorough 
cooking, especially slow boiling, will soften the connective 
tissue, and may render palatable meat that, cooked other- 
wise, would be exceedingly tough on account of the large 
amount of connective tissue. 



Imitation of Structure of Muscle. — A good way to 
represent the structure of muscle is to take a number of 
pieces of red cord to represent the muscle fibers. Wrap 
each in white tissue paper ; this represents the individual 



12 PHYSIOLOGY. 

fiber sheath. Lay a number of these side by side ; wrap 
all in a common sheath ; let the tissue paper project be- 
yond the threads, and here compress it into a compact 
cylinder ; this last corresponds to the tendon. 

Connective Tissue the Skeleton of Muscle. — If all 

the muscular tissue were removed from a muscle, the 
sheaths and partitions would remain, just as they do in a 
squeezed lemon or orange. The connective tissue forms 
a framework for all the soft tissues of the body, and if 
their working cells were removed, the connective tissue 
would remain, and show more or less completely the form 
of the part. Connective tissue, therefore, may be called 
the skeleton of the soft tissues. Muscle consists, then, 
essentially of a collection of soft, transparent tubes, filled 
with the semi-fluid muscle substance. By scraping the 
surface of a steak with a dull knife the muscle substance 
may be obtained, leaving the connective tissue. This is a 
good way to get the nutritious part of beef for an invalid. 

Importance of Muscles. — The different materials of 
which the body is built up are called tissues. Thus we 
find muscular tissue, bony tissue, nervous tissue, etc. The 
muscles make up nearly half of the> weight of the body. 
This fact of itself should lead us to consider the muscles 
of high importance. Add to this the facts above noted, 
that the muscles are so largely concerned in the nutrition 
of the body, the chief agents for its protection, essential 
for the reception of ideas, and absolutely indispensable for 
the expression of ideas, and we can see the reason for 
beginning the study of physiology with the examination 
of the muscles and their action. 

Laws of Muscle Action. — The chief characteristic of 
muscle is its ability to shorten ; incidentally, it at the 



motion: 13 

same time thickens and hardens. But it does its work by 
shortening, pulling on the bones by means of the strong, 
inelastic tendons, thus producing motion. The action of 
the muscle as a whole is the result of the characteristics 
of the cells of which it is composed. The individual cells 
and fibers shorten, and their combined action is seen in 
the muscular movement. 

Extent of Muscle Shortening. — A muscle may be 
made to shorten one third of its length, but probably 
never shortens that much in the living body. 

Duration of Muscle Shortening. — A muscle cannot be 
kept shortened for any great length of time. If one holds 
his arm out horizontally as long as possible he soon feels 
fatigue, later pain, and he may feel soreness in the muscle 
for several days. The law of muscle action is to alternate 
periods of rest with periods of action. In many exercises, 
as in walking, the limbs act alternately, one resting or 
recovering position while the other works. 

Alternate Action of Flexors and Extensors. — If we 

consider the biceps and triceps of the arm, we see that 
they are compelled to act alternately if they would do 
effective work. They might both shorten at the same 
time, and are made to do so in such an attempt as that 
of holding the arm rigidly bent at a right angle ; as, for 
instance, in wrestling " square hold," in which case one 
wishes to prevent his opponent from either pushing or 
pulling him. But while the two muscles act, no motion is 
produced. When the flexor shortens, the extensor length- 
ens, and vice versa. 

Normal Condition of Muscle. — The muscles are always 
slightly stretched, as shown by the fact that when a cut 
is made into a muscle the wound gapes open ; the tension 



14 PHYSIOLOGY. 

of the muscle is further shown by the fact that when a 
bone is broken, as in the upper arm or thigh, the ends 
of the bones slip by each other, and the limb has to be 
strongly stretched to bring the ends back together. Mus- 
cles act better when slightly stretched, and probably need 
a slight resistant action of the opponent muscle. 

Symmetrical Development of the Muscles. — The mus- 
cles of the two sides of the body are the same in number 
and arrangement. At birth they are probably about equal 
in size, weight, and strength. Most persons early become 
right-handed, and the greater use of the right hand and 
shoulder makes the muscles of this side larger and heavier. 
The muscles pulling on the bones slightly modify them 
in shape. The whole body may become noticeably un- 
symmetrical. .Most persons step harder on one foot than 
the other, as shown by the sound of the footstep, and as 
shown by the constant wearing of one shoe sole or heel 
faster than the other. In many persons one shoulder is 
habitually carried higher than the other. Symmetrical 
development should be carefully sought, and any tendency 
to a one-sided development should, so far as possible, be 
avoided. We should use the left hand more. There are 
many advantages in being able to use either hand. In 
carving, in shaving, in bandaging, in administering medicine, 
it may be necessary to use the left hand skillfully. The 
pianist and the harpist use the two hands about equally, 
while the violinist puts much more skill into his left hand. 
Trainers of athletes often begin by developing the left 
side of the body till it equals the right in size and strength. 

Muscles the Source of Strength. — Our strength de- 
pends on our muscles. It is a fine thing to have strong, 
well-developed muscles, not only because they give beauty 



MOTION. 



15 



of form, but because extra strength and endurance may 
be needed in case of accident, to save one's own life or that 
of others. In a case of fire the ability to climb, to go up 
or down a rope "hand over hand," may be all important. 
Any one's life may depend on his ability to run far and 
swiftly, to swim, to jump, or to lift a heavy weight. 

Skeletal Muscles. — When we look at the skinned car- 
cass of an animal in the market, we observe that the mus- 
cles almost completely cover the bones. Those which are 
attached to the bones are called skeletal muscles. They act 
upon them as levers, giving to motion strength, quickness, 
and precision. Without bones our motions would be like 
those of an earthworm or slug, slow and uncertain. The 
muscles, acting through the bones, can lift a weight that 
would crush the muscles if laid directly upon them, while 
a bone, able to support a heavy weight without being 
crushed, has no power in itself. The muscles have active 
strength, the bones have passive strength. 

Relation of the Muscles and the Bones. — Feel 
the biceps of your arm. Note that the thickest 
part of it is opposite the most slender part of the 
bone. But at the enlarged end of the bone the 
muscle has narrowed to a slender tendon, which 
passes over the joint to be attached to the next 
bone, thus giving more slenderness, flexibility, and 
freedom of motion to the joint. Thus muscle and 
bone fit each other, and the form of the entire limb 
is more graceful than that of the bare skeleton. 
Fig. 5 A shows how the ends of a broken bone 
overlap as a result of the tension of the muscles. 
The muscle which closes the mouth, as in pursing 
up the lips, is not attached to any bone, 
but in shortening reduces the aperture. 
The digastric muscles are slender at the 
middle and enlarged at the ends. Fig . 5 A . Fracture of the Humerus. 




16 PHYSIOLOGY. 

Flexion of the Forearm. — Take the bones of the arm that are 
articulated (if there is not an artificial hinge at the elbow, one can 
readily be made of wire) ; put a strong rubber band in place of the 
biceps muscle ; fasten this to the head of the humerus by cords, and 
by the lower end to the radius, where the rough place, an inch or so 
from the elbow joint, shows the insertion of the tendon. Have the 
rubber stretched so that when not held it will flex the forearm. This 
will serve to show the action of the biceps, though we must be careful 
to bear in mind that the muscle does not pull the arm up because it has 
been stretched, as is the case with the rubber. In the case of the 
muscle, we know that the live muscle has the power of shortening when 
stimulated, and in this respect is totally unlike the rubber. The live 
cells, or units, act in concert. 

Levers. — The essentials of a lever are the point about 
which the lever turns, called the fulcrum, the place where 
the power is applied, called the power, and the part to be 
moved, called the weight. In the body, the fulcrum is 
some joint, the power is the place where the muscle is 
attached, and the weight is the part to be moved. 

Kinds of Levers. — In flexing the forearm, the weight 
is the hand or the hand and what is in it ; the fulcrum is 
the elbow joint ; and the power is the point where the 
tendon of the biceps is attached to the radius. This kind 
of a lever is what the books call a lever of the third class. 
The triceps, on the back of the arm, pulls on the projection 
of the ulna (the inner bone of the forearm when the palm 
is up), back of the elbow. The elbow is here, also, the 
fulcrum, and the hand (or the object to be pushed by the 
hand) is the weight. This kind of lever, where the fulcrum 
is between the power and the weight, is called a lever of the 
first class. In raising the weight of the body, by stand- 
ing on tiptoe, we use a lever of the second class. Here 
the ball of the foot is the fulcrum. The weight is the 
weight of the whole body, resting on the ankle joint, while 



MOTION. 



17 



the power is the calf muscle. We may find many exam- 
ples of levers in the body if we look for them. 




(1) Tapping on Floor. (2) Rising on Toe. (3) Lifting Weight. 

Fig. 6. Three Kinds of Levers as shown by the Foot. 
P — Power. W — Weight. F — Fulcrum. 



Kinds of Levers shown by the Foot. — The different 
classes of levers may be further illustrated by different 
motions of the foot. In tapping the toes on the floor 
while the heel is lifted, or in pressing down the ball of the 
foot while running the treadle of a sewing machine, we 
have an example of a first-class lever. In raising the 
weight of the body on tiptoes, or as the foot is used in 
taking each step, the foot is used as a lever of the second 
class. When one lifts a weight with the toes, the foot is 
used as a lever of the third class. These three classes of 
levers are illustrated in the accompanying figures. 

Advantages and Disadvantages of Levers in the Body. — The 

action of the bones of the forearm as a lever may perhaps be better 
understood by the following considerations : If the arm consisted 
merely of the biceps, suspended from the shoulder, it is evident that 
its only action would be a straight pull. Suppose the biceps, thus 
hanging alone from the shoulder, had a hook at its lower end, it could, 
when it shortened, lift a weight just as far as it shortened, and no 



i8 



PHYSIOLOGY. 



reason of this lever arrangement 



Ball 



farther. It could not swing the weight outward, or push it upward. 
But from the way in which the biceps is attached to the forearm, when 
the muscle shortens an inch it may move the hand a foot. Of course 
the hand moves much faster, and we have a great gain in speed by 

But we cannot lift so heavy a weight 
at this faster rate, as we could at the 
elbow. For instance, suppose one were 
to carry a heavy basket with a bail 
handle by slipping the arm through 
the bail up to the elbow. Now, it is 
evident that the biceps is supporting 
the weight. If it is as heavy as can be 
held here, we know that we could not 
hold the same weight in the hand with 
the elbow bent at a right angle. 



Articular Extremity 



Medullary Cavity 



Hard Bone 



Study of One of the Long Bones. 

— For this, take, preferably, a femur 
or a humerus. Let us suppose we have 
a femur. 

i. Observe its shape, — cylindrical, 
somewhat curved, enlarged at the ends. 

2. The ends have smooth places, 
where they fitted other bones. 

3. Along the sides, especially near 
the ends, are ridges and projections, 
where the muscles were attached. 

4. There are small holes in the 
bone, where blood tubes passed in and 
out. 

5 . Saw a femur in two, lengthwise, 
and make a drawing showing : — 

(a) The central marrow cavity. 

(J?) The spongy extremities, noting especially the directions of the 
bony plates and fibers. 

6. Observe the width of the lower end of the femur, where it rests 
on the tibia. Suppose these two bones were as narrow at their ends, 
where they meet to form the knee joint, as they are at their centers, 
what kind of a joint would they make ? Illustrate by piling up a num- 



— Spongy Bone 

Articular Extremity 

Fig. 7. Longitudinal Section of 
Femur. 



MOTION. 



19 



ber of spools on end ; the column is more lightened than it is weak- 
ened by the hollowing out of the sides of each spool. And the central 
hollow of the spool does not greatly weaken it. A given weight of 
material has more strength when in the form of a hollow cylinder. The 
bones combine well two very desirable quali- 
ties, lightness and strength. If in our col- 
umn of spools we place a wide rubber band 
around the junction of two spools, we have 
something very similar to the capsular liga- 
ment, which surrounds the joints. 

Joints. — The ends of the bones, where 
they fit together in the joints, are covered 
with a layer of smooth, elastic, whitish or 
transparent cartilage. The motion in the 
joints is made still more easy by the synovia, 
resembling white of egg. The ends of the 
bones are held together by tough bands and 
cords of ligament, a form of connective 
tissue very much like tendon. Bones are 
closely covered by a tough coat of connective 
tissue called the periosteum. 

All these structures can easily be found 
by dissecting a sheep shank gotten from the 
butcher, or in the hind leg of a rabbit. 

Locomotion. — Locomotion is mov- 
ing from place to place and should 
be distinguished from mere motion. 
By continuing such observations as 
we made when we began to study 
our motions, we can analyze and 
understand many of the common 
movements which we habitually 
make. 

Standing. — Although we are not ordinarily conscious of 
the fact, when we are standing still we are using many 
muscles. The accompanying figure illustrates how some 




Action of the Muscles 
in Standing. 



20 PHYSIOLOGY. 

of the muscles act in keeping the body upright. Our 
weight, or, we would better say, the force of gravity, is 
continually trying to pull us down to the ground. The 
joints are all freely movable, and hence as soon as the 
muscles cease to act properly, in balancing against each 
other, we lose our equilibrium, and fall if we do not 
quickly regain it. 

Walking. — In walking, we lean forward, and if we take 
no further action we fall. But we keep one foot on the 
ground, pushing the body forward, while the other leg is 
flexed and carried forward to save us from the fall. We 
catch the body on this foot, and repeat the action. To 
show how we are really repeatedly falling and catching 
ourselves, recall how likely one is to fall if some obstacle 
is placed in the way of the foot as it moves forward to 
catch the weight of the body. 

Running. — In running, the action is more vigorous. 
The propulsion by the rear leg is now greater. It gives 
such a push as to make the body clear the ground, whereas 
in walking, the rear foot is not lifted till the front foot 
touches the ground. But in running there is a time when 
both feet are off the ground. 

Locomotion by Reaction. — Take two broomsticks and place them 
crosswise under the ends of a board. Run along the board. This 
shows that the direct effort in running is to push one's support from 
under him. When a horse plunges forward in the mud, he only thrusts 
his feet farther into the mud. Our effort in progression is primarily to 
push the earth out from under us, and it is by reaction that we go 
forward. It is the same problem with the fish swimming forward by 
striking backward and sideways against the water, and with the bird 
beating downward and backward upon the air. 

Bones combine Lightness and Strength. — The mus- 
cles, then, make use of the bones as levers.- We carry 



motion. 21 

these levers with us all the time. Hence the desirability 
of having them as light as is consistent with the requisite 
degree of strength. The body follows the same law of 
mechanics that we use outside of the body. A hollow 
pillar or hollow tube has a greater strength than the same 
amount of material in the form of a solid cylinder. The 
long bones of the limbs are hollow, and near their ends, 
where we have found that they need to be enlarged, we 
find a spongy structure, where lightness and strength are 
secured by the interlacing fibers and plates of bony 
material. 

Uses of Bones. — The part that the bones play is of a 
passive nature ; they support the tissues, protect some 
parts, and serve as levers on which the muscles act. We 
may not call the bones dead tissues, for they receive blood 
and grow. But the active muscles use them as a man uses 
a crowbar, as a mere tool. It will therefore be more 
interesting to return to the muscles, and learn the causes 
and conditions of their activity. 

What makes Complex Muscular Action Harmoni- 
ous. — Have you ever seen two persons, each using the 
right hand, try to sew, one holding the cloth, the other 
using the needle ? Would they get along well ? Suppose 
one were to hold the needle, and the other were to try to 
thread it, each using one hand ? Why is it that the right 
hands of two persons cannot work so well together as the 
right and left hands of one person ? What connection is 
there between the two, that one knows just what the other 
is doing and when it does it ? Why can two individuals 
never, with any amount of practice, work so in unity as the 
parts of the individual ? 



22 PHYSIOLOGY. 

Let us seek the answers to these questions in the fol- 
lowing lessons. 

Alcohol and Muscular Energy. — Alcohol does not in- 
crease the energy of the body so far as muscular work is 
concerned. Repeated experiments have been made which 
show that power to do muscular work is diminished as the 
result of taking alcohol. The person may, and often does, 
feel stronger, but the feelings are neither a sure test nor 
a safe guide. As one writer says, the drunken man thinks 
he is strong enough to hold two men, whereas he needs 
two men to support him in his weakness. Test of ability 
to do work shows the weakening effect of alcohol. It was 
formerly supposed that when men were called upon to 
perform unusually hard work they needed the sustaining 
power of alcoholic liquor, and such drink was furnished 
to men engaged in harvesting, etc. This belief has been 
thoroughly disproved. 

The apparent liveliness of the tipsy person, and his 
more or less violent gesticulations, are no sign of added 
strength. We all know that restlessness and nervous 
activity are often a sign of weakness and not of strength. 

Alcohol and Training. — It is a significant fact that men 
who are training for athletic contests (no matter what their 
ordinary habits or principles are) let alcoholic drinks alone. 
One of the famous pugilists said, " I'm no teetotaler, but 
when I have business on hand there's nothing like water 
and dumb-bells." No schoolboy or college student can 
hope to gain a place on any athletic team if he indulges 
in alcoholic drink. 

Reading. — How to Get Strong and How to Stay So, 
Blaikie ; Sound Bodies for Our Boys and Girls, Blaikie ; 
Physiology of Bodily Exereise } Lagrange. 



MOTION. 23 

Summary. — 1 . Motion is involved in nearly every activity of the body. 

2. The action of muscle is a shortening, accompanied by a thicken- 
ing and hardening. 

3. Muscle consists of fibers with a connective tissue sheath for 
each fiber, bundle of fibers, and for the muscle as a whole. 

4. The skeletal muscle fibers are striated. 

5. The muscles make about half the body's weight. 

6. Muscles may shorten one third their length. 

7. They cannot remain shortened long for a time. 

8. The muscles should be developed symmetrically. 

9. In the limbs the muscles are fusiform and have their greatest 
diameter opposite the central, or narrower, portions of the bones, con- 
cealing the fact that the bones are largest at the ends, as is so manifest 
in the skeleton. 

10. The bones serve as levers by which the muscles exert their force. 

11. The bones of the limbs are hollow cylinders combining light- 
ness and strength. 

12. The joints have a smooth motion due to the cartilage and 
synovia. 

13. Locomotion is brought about by reaction. 

Questions. — 1. What effect is produced by carrying a heavy satchel 
for a long distance without resting? 

2. Which is more tiresome, standing still or walking? Why? 

3. When the boy, who thinks he can strike a hard blow, says, 
u Feel my muscle," does he usually call attention to the muscle used in 
striking ? 

4. Find other examples of levers in the body. 

5. Find examples of the three kinds of levers, not in the body, 
which we use often. 

6. Why is it easier to sit with one leg crossed over the other? 

7. What is the effect on muscles of light clothing? 

8. How may the arms be used to illustrate the three kinds of 
levers ? 

9. Analyze and explain jumping, hopping, etc. 

10. What is "curvature of the spine"? How caused and how 
avoided ? 

11. What makes people bow-legged? 

12. Why are the sides of the body often sore after walking on icy 
pavements ? 



CHAPTER III. 

THE GENERAL FUNCTIONS OF THE NERVOUS SYSTEM. 
— SENSATION AND MOTION. 

What makes Muscles Shorten ? — We have seen that 
the muscles have the power of shortening ; that in shorten- 
ing they act on the bones as levers to produce our varied 
motions. What makes the muscles shorten ? 

Voluntary and Involuntary Motions. — Some motions 
we will to make. We will to sit, to stand, to walk, to run, 
or to stretch out the hand. Such motions, originating in 
a brain activity, are called Voluntary. Other motions are 
Involuntary. The will does not control the heart beat. 
Most persons cannot keep from winking when a quick 
motion is made toward the face, even if they know they 
will not be hit. But all of these motions, whether volun- 
tary or involuntary, are dependent upon the nervous 
system. 

The Cerebro-spinal Nervous System. — This consists 
of the brain, the spinal cord, and the spinal nerves. The 
brain will be described later. 

The Spinal Cord. — The spinal cord is a cylindrical 
body extending from the brain along the cavity of the 
spinal column. Its diameter is not uniform throughout. 
Between the shoulders is an enlargement called the cer- 
vical enlargement, where the large nerves are given off to 

24 



NERVOUS SYSTEM. 



25 




Fig. 9. Diagram showing Arrangement of Nervous System 



26 PHYSIOLOGY. 

the arms. In the region of the loins is the lumbar enlarge- 
ment, where the nerves are given off to supply the poste- 
rior limbs. The cord is not so long as the cavity of the 
spinal column, and the space posterior to the cord is occu- 
pied by the nerves extending to the posterior limbs, and 
these nerves are given off at a very sharp angle, and con- 
tinue backward for some distance before they emerge 
from the cavity of the spinal column. But in the region 
of the shoulders the nerves spring off at about a right 
angle with the cord. The outside of the cord is white, but 
the central portion consists of what is called gray matter. 
The white portion is made up of fibers, but the gray matter 
consists of nerve cells as well. 

The Spinal Nerves. — These are given off in pairs from 
the sides of the spinal cord, passing out between the suc- 
cessive vertebrae. In the regions of the shoulders and 
loins the spinal nerves are large, as they supply the large 
muscles of the limbs ; but in the middle of the back, where 
only the muscles of the body wall are supplied, the nerves 
are small. We have thirty-one pairs of spinal nerves. 

The Roots of the Spinal Nerves. — Each spinal nerve 
arises by two roots, one nearer the back, called the dorsal 
root, the other nearer the ventral surface, the ventral root. 
These two roots soon unite to form one spinal nerve. 

The Ganglion of the Dorsal Root. — On the dorsal 
root, just before it unites with the ventral root, is a swell- 
ing, the ganglion of the dorsal root. Like all ganglions, it 
is largely made up of nerve cells, being a center of con- 
trol rather than a means of communication. This ganglion 
appears to control the nutrition of the adjacent nerve fibers, 
and is not concerned in the process of reflex action. 



NERVOUS SYSTEM. 2J 

A Model of the Cerebro-Spinal Nervous System. — A 

plaster of Paris or papier-mache model of the cerebro- 
spinal nervous system will prove very helpful at this 
point. A study of it will show how the spinal cord is 
snugly and safely inclosed within the spinal column. At 
the joints between adjacent vertebras there are openings 
through which the spinal nerves pass out without danger 
of being crushed, or even pinched when the backbone 
bends. It will be noted that the nerves given off in the 
regions of the shoulders and hips are large, while in the 
middle of the back they are small. In the middle of 
the back only the body-wall is to be supplied with nerves, 
while we would naturally expect large nerves for the 
powerful muscles of the fore and hind limbs. 

Structure of Nerves. — When we trace the sciatic nerve 
outward, we find that it is continually subdividing. This 
division continues until the branches are too small to be 
seen by the naked eye. Microscopic examination shows 
that a nerve is made up of a great number of fibers bound 
together in a common sheath of connective tissue, as is 
the case with muscle. When the nerve divides there is 
ordinarily no true branching or forking, but certain of 
the fibers simply separate from the rest, as in the separa- 
tion of the fibers in floss silk. 

Structure of a Nerve Fiber. — A single nerve fiber is 
too small to be seen by the naked eye, being only about 
one two-thousandth of an inch in diameter. It consists of 
the following parts : — 

1. The Axis Cylinder, a central strand, or core, of semi- 
transparent, gray material. 

2. The Medullary Sheath is a layer of white, oily 
material around the axis cylinder. 




28 PHYSIOLOGY. 

3. The Nerve Fiber Sheath is a thin, transparent outer 
sheath of connective tissue. 

Function of Nerve Fibers. — The sole function of the 
nerve fiber is to convey nerve impulses. The nerve im- 
pulse passes along the axis cylinder as an electric current 
passes along an insulated wire. 

Nerve Fiber Sheath 



Axis Cylinder 



Medullary Sheath 
Fig. 10. Structure of a Nerve Fiber. 

Afferent and Efferent Nerve Fibers. — Nerve fibers that 
carry impulses to the brain or spinal cord are afferent nerve 
fibers. Fibers that convey impulses from the brain or 
spinal cord are efferent nerve fibers. 

Cross-section of the Spinal Cord. — If a thin slice of 
the spinal cord be made as shown in Fig. n, it will be 
seen that the central part is darker in color than the outer 
part. The central part is known as the gray matter, in 
distinction from the rest, which is called the white matter. 
The white matter of the nervous system is made up of 
nerve fibers whose structure and use we have just con- 
sidered. But the gray matter has a different structure and 
a different function. Instead of being made up mainly of 
fibers it is composed of cells, one of the forms of which is 
represented in Fig. 12. Some of the branches of these 
cells are continued, and become the axis cylinders of nerves, 
and it is believed that every nerve fiber begins as a branch 
of some nerve cell. One of the best places to see these 
nerve cells is in the gray matter of the spinal cord, near 



NERVOUS SYSTEM. 



29 



the place where the ventral root of the spinal nerve arises. 
This part of the gray matter is called the ventral horn of 
the gray matter. If this portion be examined under a 
moderately high power of the microscope, there may be 
seen a number of cells with radiating branches. 

Dorsal Septum 



Dorsal or Sensor__ f//^ 
Root 




Ganglion 



Ventral or Motor Root 

Fig. 1 1 . Cross-section of Spinal Cord. 

Functions of the Spinal Cord. — The spinal cord has 
two main functions : — 

1. Its conducting power, by means of the white fibers 
which make up the outer part of the cord. These fibers 
may be regarded as connecting the gray matter of the 
brain with all parts of the body. 

2. The gray matter is the center of the reflex actions of 
the cord. 

Ganglia. — Masses of nerve cells make up nerve centers, 
or ganglia, such as are on the dorsal roots of the spinal 
nerves. These also would show under the microscope 
that their chief constituent is a collection of nerve cells 
which give off one or more branches. 



30 PHYSIOLOGY. 

The gray matter of the spinal cord is considered a col- 
lection of ganglions. We see that the outer layer of the 
brain is grayish in color. Within is white matter, consist- 
ing of nerve fibers that connect the cells of the gray layer 



Branched Processes 




Unbranched Process 



Fig. 12. A Large Nerve Cell from the Gray Matter of the Spinal Cord. 

with the various parts of the body through the base of the 
brain, the spinal cord, and spinal nerves. 

No Sensation without the Brain. — After a fowl's head is cut off it 
" flops " around for some time, and it may even jump clear from the 
ground. If one takes hold of its feet to pick it up, it may begin to 
struggle as if it were trying to escape. 

Now, we know that the bird cannot feel anything after its head is 
cut off, because the body is completely separated from the brain, which 
is the center of sensation. So with the frog. After its head is cut 
off, it cannot feel anything. 

Reflex Action of the Spinal Cord of the Frog. — A frog may be 
killed as directed on p. 9. Cut off its head and suspend the body 
from any convenient support, such as the ring of a retort stand. 

1. On pinching the toes the foot will be drawn up. 

2. The sciatic nerve should now be severed as before directed 
(p. 9). At the instant of cutting the nerve the muscles below will 
twitch, because the nerve fibers running to them are stimulated. 



NERVOUS SYSTEM. 



3.1 



3. If the toes are again pinched, it is found that the uninjured leg 
will draw up, but not the one whose sciatic nerve has been severed. 

4. If a wire be run down the spinal cavity, the spinal cord will be 
destroyed, and during the operation the uninjured leg will act spas- 
modically, because the nerve fibers going to its muscles from the cord 
are stimulated. 

5. Pinching the toes no longer gives response, because the cord, 
which acted as the center of this reflex action, is destroyed. 

The Gray Matter of the Cord the Center of Reflex 
Action. — In simple sensation of touch, pressure on the 

Afferent Dorsal Root 

Sensor Fiber .- 




Muscle 



Motor Fiber 
Efferent 



Ventral Root 



Fig. 1 3. Diagram of Reflex Action of the Spinal Cord. 
(After Landois and Stirling.) 

toes starts a nerve current or nerve impulse which runs up 
to the brain. The sensation is in the brain, but is referred 
to the foot. Hence we should be careful not to speak of 
a sensation being carried. In voluntary muscular action 
the impulse starts from the brain, goes to the muscles, and 
makes them shorten or relax. 

But in reflex action the current runs up the nerve to the 
spinal cord. The gray matter of the central part of the 
cord receives the message, and sends back a nerve impulse 
to the muscles to make them shorten and pull the foot 
away from the source of injury. 



32 PHYSIOLOGY. 

The Parts Essential to Reflex Action of the Spinal 
Cord : — 

i. A sensitive surface (the skin, for instance). 

2. Afferent nerve fibers. 

3. A nerve cell, or cells, in the center of the spinal cord. 

4. Efferent nerve fibers. 

5. Working organ, as muscle or gland. 

Phases of Reflex Action. — In the above experiment 
on the frog the steps in order were : — 

1. Stimulation of the nerve endings in the skin of the 
toe. 

2. Passage of a nerve impulse up the afferent fibers to 
the spinal cord. 



Nerve-Cell 



Afferent Fiber 



Skin — . 




— Efferent Fiber 



— Muscle 
Fig. 14. Scheme of Reflex Arc. 



3. Reception of the impulse by a cell, or cells, of the 
gray matter in the cord. 

4. Sending back a nerve impulse 

5. Along an efferent fiber, or fibers, to 

6. Muscles which shorten and move the foot. 

Importance of Reflex Action. — It is important that 
we understand the nature of reflex action, for very many 
of the processes of the body are regulated by it. Not 
only the more manifest motions, such as winking when 



NERVOUS SYSTEM. 33 

anything comes quickly toward the eye, dodging, jumping 
when suddenly touched by anything hot or when pricked 
by a pin, but also the adjustments of the essential processes 
of life, circulation, respiration, and digestion, are brought 
about through reflex action. 

Destination of Nerve Fibers. — The sciatic nerve is 
composed of many fibers. If this nerve is traced outward, 
it is found to be continually subdividing, and sending small 
branches to the muscles, and finally in the muscles one 
fine nerve fiber goes to each muscle fiber. (See Fig. 5.) 
Many fibers go on past the muscles to the skin. We can 
feel in any .part of the skin, and we can tell just where we 
are touched. These fibers from the skin, then, carry 
nerve impulses inward, as those going to the muscles 
carry impulses outward. 

Nerve Roots and their Functions. — Observations 
made on animals, and accidents in the case of man, show 
that all the fibers of the nerves that carry currents to the 
muscles pass out from the spinal cord into the ventral 
root, and that all the fibers that carry currents inward 
enter the spinal cord through the dorsal root. Hence, the 
dorsal root is often called the afferent root, and the ventral 
the efferent root. Since ingoing impulses produce sensa- 
tion, the dorsal root is called the sensory root, while the 
ventral root, carrying currents outward to produce motion, 
is called the motor root. 

Effect of Stimulating a Spinal Nerve. — Experiments 
have shown that if, in an uninjured animal, a nerve, or 
more properly a nerve trunk, — as the sciatic nerve, — be 
stimulated, for instance, by a suitable electric shock, two 
effects are produced : first, motion in the parts whose 



34 PHYSIOLOGY. 

muscles are supplied by the nerve ; second, sensation, 
which is referred to the parts of the skin supplied by the 
branches of the nerve. 

Effect of Severing a Spinal Nerve. — If, instead of simply stimu- 
lating the nerve, the nerve is severed, the same two effects will be pro- 
duced. After severing the nerve, if we stimulate the end of the nerve 
still connected with the limb, we get action of the muscles in that limb. 
If we stimulate the end of the nerve connected with the body, a sensa- 
tion will be produced, and this sensation will be referred to the parts 
from which the nerve fibers arise, probably in the skin of the limb. 

Effect of Stimulating the Ends of Severed Nerve Roots. — If we 

now turn to the roots of the nerve, and make similar experiments, we 
obtain the following results : Stimulating the dorsal root causes sensa- 
tion referred to some outer surface, and no other effect is noticed. 
Cutting the dorsal root also causes sensation. Stimulating the end of 
this root still connected with the spinal cord causes sensation ; but 
stimulating the end of the root connected with the nerve gives no 
appreciable result. 

Stimulating or cutting the ventral root causes motion in the parts 
whose muscles are supplied by fibers from this root. After severing 
this root, if the end connected with the spinal cord be stimulated, no 
effect is noticed ; but stimulating the end still connected with the nerve 
is followed by shortening of the muscles supplied. 

Effect of Severing All the Spinal Nerves. — Severing 
all the spinal nerves destroys all power of sensation and 
voluntary motion in all parts of the body except the head. 
After severing all the dorsal roots, no sensation would be 
produced by stimulating any part of the body, and after 
severing all the ventral roots no act of the will can cause 
any of the muscles of the body to act. Severing all the 
nerves, or severing all the roots, cuts off all communication 
o^the brain with the body, and, so far as motion and sensa- 
tion in the body generally are concerned, has the same 
effect as severing the spinal cord below the head. 



NERVOUS SYSTEM. 35 

Cramp. — Cramp is a spasmodic shortening of the 
muscles, attended with pain. 

Tetanus. — Tetanus (or locked jaw) is a spasmodic and 
continuous shortening of the muscles, causing rigidity of 
the parts they supply. It is due to the disordered and 
excessive stimulation of the muscles through the nerves. 

Crossing of the Fibers from the Brain to the Spinal 
Cord. — Both the brain and the spinal cord consist of two 
lateral halves connected by cross fibers. Each half of the 
brain is connected with the opposite half of the body. 
This is accomplished by the crossing of the fibers. The 
fibers that carry nerve impulses outward are now known 
to cross as they leave the brain, at the very beginning of 
the spinal cord, in the part known as the spinal bulb. 
The sensations arising from touching anything with the 
right hand, therefore, are in the left half of the brain, and 
the right half of the brain controls the left hand. 

Voluntary Interference with Reflex Actions. — We 

have seen that the jerking of the hand away from a hot 
object is due to reflex action of the spinal cord. One 
might, by a powerful effort of the will, keep the hand on 
an object that is hot enough to burn the skin. One may 
command the foot to remain quiet when it is tickled ; but 
as soon as the person is asleep, the same stimulations 
would be followed by the reflex actions such as we have 
considered. 

In these cases of interference it is understood that the 
brain sends a nerve impulse down to the centers of the 
reflex action, and stops or diminishes their operation. 
This retarding influence of a group of cells is called inhi- 
bition. It is not always due to voluntary interference, 
but may be due to reflex interference, as we may see later. 



36 PHYSIOLOGY. 

The Nature of a Nervous Impulse. — Of the nature 
of a nerve impulse we know but little. It is convenient 
to compare the nervous system, with its conducting fibers 
and central ganglia, to a telegraph system. And electric- 
ity is the most convenient stimulus for exciting nerve im- 
pulses. Yet a nerve impulse is very different from an 
electric current. A nerve fiber is a poor conductor of 
electricity. An electric current may travel along a copper 
wire at the rate of between 100,000 and 200,000 miles a 
second, while a nerve impulse in a motor nerve travels 
only 170 feet in a second. 

Transmission of Motor Impulses, — When a motor fiber is stimu- 
lated in the middle of its course we observe only one effect, — the 
shortening of the muscle at its lower end. But there is every reason 
to believe that the nerve current, or impulse, runs along the nerve in 
both directions from its starting point. But while the action of the 
muscle at the peripheral extremity manifests the existence of the cur- 
rent, there is nothing at the central extremity to give such evidence. 

Transmission of Sensory Impulses. — Similarly, when a sensor 
nerve fiber is stimulated at some intermediate point, we have a sensa- 
tion in the brain due to the current brought by the afferent fiber, and 
which we refer to the outer end of the nerve fiber. Probably a nerve 
impulse passed from the point of stimulation to the outer end of the 
fiber ; but as there is nothing at the outer end of the nerve fiber Jo 
interpret it, we get no evidence of such impulse except by refined 
physiological tests. 

Harmony in Muscle Action. — In throwing a stone a 
number of muscles are used. Each one of these must 
shorten in the right way and at the right time or the throw 
will not be accurate. Each muscle shortens under the 
influence of a nerve impulse started by the brain and 
brought by a motor nerve. If any muscle shortens an 
instant too soon, or a little too strongly, the stone goes to 



NERVOUS SYSTEM. 37 

one side. In a tune on a piano we know that the right 
keys must be struck ; that each must be struck at the right 
time, with the proper degree of force, and held for the 
right length of time, or we have discord instead of har- 
mony. What the player is to the instrument, the brain 
is to the body. 

Temporary Loss of Muscular Power. — It may have 
happened to you that after sitting long in one position you 
attempted to stand, but found that you could not do so 
One leg failed to act at the bidding of your will. When 
the foot is "asleep" we get little sensation from it; we 
hardly know whether it is touching the floor or not. Press- 
ing on it with the other foot causes no pain. 

We try to stand when the foot is asleep, but we are 
unable to do so. The brain starts the nerve currents, and 
they run along the nerve as far as the compressed part ; 
here they stop. They cannot reach the muscles of the 
leg below. Hence the muscles do not shorten, and we 
do not rise, no matter how strongly we will to do so. 

Why is it that the nerves and muscles thus sometimes 
lose their ability to perform their natural activities ? 

Dependence of Nerves and Muscles. — This has been 
explained by saying that owing to external pressure, the 
nerve has temporarily lost its power of conducting nerve 
currents. But what beside the nerve has been com- 
pressed ? What process in the limb has been interfered 
with by the pressure due to the position in which one has 
been sitting or lying ? What is the temperature of the 
benumbed limb ? 

On what are the nerves and muscles so dependent for 
the maintenance of their activity? 



3$ PHYSIOLOGY. 

Reading. — Power through Repose, Call ; The Technique 
of Rest, Brackett ; Muscles and Nerves, Rosenthal. 



Summary. — i. Motions are voluntary or involuntary, but all are 
under control of the nervous system. 

2. The cerebro-spinal nervous system consists of the brain, the 
spinal cord, and the spinal nerves. 

3. Each spinal nerve has two roots: the dorsal, which is afferent 
and sensory ; the ventral, which is efferent and motor. 

4. A ganglion is a nerve center largely composed of nerve cells. 

5. Nerves are made up of nerve fibers. 

6. A nerve fiber consists of the central core (or axis cylinder), 
which conducts the nerve impulse, the medullary sheath, and, outside, 
the nerve-fiber sheath. 

7. The spinal cord has in its outer part white nerve fibers, in its 
center gray nerve cells. 

8. These cells are branched, and at least one branch becomes the 
axis cylinder of a nerve fiber. 

9. The gray matter of the cord is the center of the reflex action. 

10. The nerve fibers from each half of the brain connect with the 
opposite half of the body. 

1 1 . The nervous system is comparable to a telegraph system. 

Questions. — 1. Name as many involuntary motions as you know. 

2. What other cases of reflex action do you know ? 

3. The story is told of a young Roman (Mucius Scaevola) that to 
show his fortitude he thrust his hand into the fire and held it there 
until it was destroyed. What physiological action does this illustrate ? 

4. Why is a man partially paralyzed when he has broken his neck 
or back ? 

5. How does the nervous system differ from a telegraph system? 



CHAPTER IV. 
CIRCULATION OF THE BLOOD. 

The Blood and its Work. — We know that if any animal 
is bled freely, it soon becomes weak, then unconscious, and 
soon dies, if the escape of blood be not stopped. 

We observe the natural difference in color of different 
parts of our bodies ; for instance, the lips and cheeks. 
We often note varying color, as in blushing and pallor. 

We wish to understand these differences and changes ; 
also to know what to do in case of fainting or bleeding 
from wounds. We may prolong and make more useful 
our own lives and those of others by knowing, in a practical 
way, something about the causes, prevention, and remedies 
of the colds, congestions, and inflammations to which we 
are subject. 

Nearly every part of the body bleeds when cut. There 
is no bleeding when we trim the nails or cut the hair, and 
the outer skin has no blood in it. But the inner skin, and 
almost every tissue within it, if pierced even by the finest 
needle, yields blood. We see a little blood oozing from 
the surface of a fresh steak or roast. 

What kind of a substance is the blood ? Is it uniformly 
distributed through the tissues, like water soaked up into a 
cloth, or is it in distinct cavities ? Why is it so essential to 
life ? How does it do its work ? 

The Rate of the Heart Beat. — The heart beats about 
seventy-two times a minute in men ; in women, about 

39 



40 PHYSIOLOGY. 

eighty. At birth the rate is from one hundred and thirty 
to one hundred and forty, and gradually decreases till 
about the age of twenty, when the average of seventy-two 
is reached. This rate holds till old age, when it increases. 
The rate is increased by muscular activity, food, external 
heat, internal heat (fever), pain, and mental excitement. 
Music accelerates the pulse rate. The pulse rate varies 
during the twenty-four hours, being lowest during the 
night, and highest about 1 1 a.m. Certain diseases increase 
the frequency of the pulse. Some drugs quicken the pulse 
rate, and others diminish it. 

To Head and Arms 



Pre-caval Vein 



Right Au 




Pulmonary Artery 
Left Auricle 



Left Ventricle 



Apex 
Fig. 14 a. The Heart, from the front. 

The Position of the Heart. — The base of the heart is 
in the center of the chest, just back of the breast bone, 
but the apex points downward and to the left. 

The Covering of the Heart. — The heart is inclosed in 
a loosely fitting membranous bag, the pericardium. Within 
the pericardium and around the heart is a small quantity 
of liquid, called the pericardial fluid. 



CIRCULATION OF THE BLOOD. 



4* 



The Size of the Heart. 

size of his clenched hand. 



A person's heart is about the 



The External Features of the Heart. — The heart is 
cone-shaped and the bulk of it is made up of the ventricles, 
the auricles being two ear-like flaps at the base, one on 
each side. There is a deep notch between the auricles 
and the ventricles. The line of division between the two 
ventricles is marked by a groove, which runs obliquely 
along the ventral surface. In this groove are blood tubes 
and usually considerable fat. 



Aorta 

Left Pulmonary Artery 

Left Pulmonary Veins 

Left Auricle 




Pre-caval Vein 

Right Pulmonary Artery 

Right Pulmonary Veins 



Post-caval Vein 



Right Auricle 



Fig. 14 b. The Heart, from behind. 



The Internal Structure of the Heart. — The two halves 
of the heart are completely separated from one another 
by a partition. Each half, in turn, has valves which, 
part of the time, separate the cavity of each auricle (at 
the base) from the cavity of the corresponding ventricle 
(at the apex). 



42 PHYSIOLOGY. 

The Valves of the Heart. — Between the auricles and 
the ventricles are curtain-like valves, whose upper edges 
are attached to the inner surface of the walls at the upper 
margin of the ventricle. These flaps are somewhat tri- 
angular, and have strong, white, tendinous cords extending 
from their edges and under surfaces to the walls of the 
ventricle below. In the right half of the heart there are 
three flaps, and this valve is called the tricuspid valve. In 
the left side there are two flaps, which, together, constitute 
the mitral valve. As these valves are between the auricles 
and the ventricles, they are called the auriculo-ventricular 
valves, or, for short, the aur-vent valves. 

The Semilunar Valves. — From the base of the right 
ventricle arises the pulmonary artery. Within its base, 
just as it leaves the ventricle, are three pocket-like valves, 
like " patch-pockets." They are in a circle, with their edges 
touching, and thus surround the opening, with their mouths 
opening away from the heart. A similar set of valves are 
within the base of the aorta, which arises from the left 
ventricle. Both these sets of valves are called ventriculo- 
arterial, or, for short, vent-art valves. 

The Blood Tubes connecting the Heart with Other 
Organs. — The aorta (the largest artery in the body) 
arises from the base of the left ventricle, and supplies 
with blood every organ of the body except the lungs. 
The pulmonary artery springs from the base of the right 
ventricle and sends blood to the right and left lungs. 
Two large veins enter the right auricle, the precaval vein 
from the anterior regions of the body and the postcaval 
vein which brings blood from all the organs of the poste- 
rior portions of the body. The pulmonary veins return the 
blood from the lungs to the left auricle, two from each lung. 



CIRCULATION OF THE BLOOD. 



45 



The Distribution of the Arteries and Veins. — The 

organs of the body receive a supply of blood in propor- 
tion to their size and activity. The artery supplying the 
blood and the vein which returns it usually lie side by side 
(see Fig. 16). The larger arteries are usually deep-seated 
and in protected places. 

Demonstration of the Action of the Heart. — The heart may be 
mounted as shown in Fig. 17, and its action illustrated by compressing 
the ventricles with both hands. Instead of the apparatus here shown 
two retort stands may be used, though not so convenient. 




Capillaries 
of the Body 



Fig- 17. Demonstration of the Action of the Heart (Heart Diagrammatic). 



The Action of the Heart. — The heart consists of 
muscle fibers so arranged that they form a thick-walled 
bag, which stands expanded when the muscles relax. But 
when the fibers shorten the whole heart contracts, and the 



4^ PHYSIOLOGY. 

cavity is much reduced in size, if not entirely obliterated, 
and the blood is forced out. 

The complete action of the heart consists of three parts, 
— the contraction of the auricles, the contraction of the 
ventricles, and the pause. 

The Pause. — During the pause the blood is steadily 
pouring into the auricles ; into the right auricle from the 
caval veins, into the left auricle from the pulmonary veins. 
At this time the curtain-like valves between the auricles 
and the ventricles are open, and their flaps hang loosely 
beside the walls of the ventricles. The blood, therefore, 
as it passes into the auricles, passes on into the ventricles. 
As the ventricle fills, the valves float up, as seen in the 
experiment of pouring water into the ventricle. 

The Contraction of the Auricle. — When the ventricle 
is full, but not stretched, and the auricle partly full, the 
auricle suddenly contracts, thus forcing more blood into 
the ventricle, and distending it. At the same time the 
aur-vent valves, already nearly closed, are tightly closed 
by the pressure of the blood which is forced up behind 
them. The flaps of the valves are kept from going up too 
far by the tendinous cords and by the papillary muscles to 
which the cords are attached. 

The Contraction of the Ventricle. — Next comes the 
contraction of the ventricle, slower, but more powerful 
than that of the auricle. As the walls of the ventricle are 
drawn together, the blood is under pressure. It cannot 
go back into the auricles, for the more it presses against 
the aur-vent valves, the more tightly they are closed. The 
semilunar valves are closed by back pressure in the aorta 
and pulmonary artery. But the pressure of the blood in 
the ventricles is so much greater that the semilunar valves 



CIRCULATION OF THE BLOOD. 



47 



are forced open, and nearly all the blood is driven out of 
the ventricles ; from the right ventricle into the pulmonary 
artery, and from the left ventricle into the aorta. 

While the ventricles are contracting and forcing their 
blood out, the auricles are slowly filling by the steady 
inflow through the veins. 

Systole and Diastole. — The contraction of the heart is 
called the systole, and its dilation the diastole. 

Dilation of the Ventricle. — As soon as the ventricle 
has completed its contraction it dilates, and most of the 
blood that has accumulated in the auricle simply falls into 
the ventricle. The dilating ventricle exerts a slight suc- 
tion, so the blood is in part drawn into the ventricle. Dur- 
ing the remainder of the pause the blood accumulates in 




Fig. 1 8. Diagram of the Heart, showing the Action of the Valves. 

the auricle and ventricle till the auricle again contracts and 
the cycle is repeated. This is true of both halves of the 
heart, which work simultaneously, the right heart pumping 
dark blood while the left heart pumps bright blood. The 
left ventricle is thicker walled and stronger than the right. 



48 PHYSIOLOGY. 

Functions of the Auricle. — The auricle has three 
functions : ( I ) to complete the filling of the ventricle ; (2) to 
complete the closing of the aur-vent valves ; (3) to act as a 
reservoir for the blood entering the auricle while the ven- 
tricle is contracting, that is, while the aur-vent valves are 
closed. 

The Function of the Ventricle. — The contraction of 
each ventricle forces the blood around to the ventricle of 
the other side of the heart. 

Work and Rest of the Heart. — The auricle contracts 
about one eighth of the time and rests the other seven 
eighths. The ventricle contracts about three eighths of the 
time, and dilates during about five eighths. Since the con- 
traction of the ventricle immediately follows that of the 
auricle, one half of the time is occupied by the whole con- 
traction of the heart, and during half the time the heart is 
resting. No part of the heart works longer than a man 
who works nine hours a day. 

The ratio of work and rest is about the same whether 
the heart is beating slowly or beating rapidly. 

Auricle contracting (working) \ of the time = 3 h., resting 21 h. 
Ventricle contracting (working) f of the time = 9 h., resting 15 h. 

It is often said that the heart never rests. Its work and 
rest follow each other at such short intervals that we do 
not realize that an interval of rest follows every beat. 
Suppose a policeman had the power of sleeping at will, and 
that he slept thirty minutes of each hour, and that in the 
remaining thirty minutes he made the rounds of a block. 
If we saw him passing regularly once an hour, every hour 
of the twenty-four, we might suppose that he did not sleep 
during the entire time. 



CIRCULATION OF THE BLOOD. 



49 



The Beat of the Heart. — The apex of the heart is 
always in contact with the chest wall. Consequently, it 
never strikes it. At each beat it pushes hard against the 
chest wall. This push may be felt and seen, and is called 
the heart beat. 

The Sounds of the Heart. — There are two sounds of 
the heart : — 

1. A short, sharp sound made by the closing of the semi- 
lunar valves. 

2. Just preceding this sound a longer, duller sound may 
be heard during the contraction of the ventricles. This is 
supposed to be due to the vibrations of the walls of the 
ventricles and of the aur-vent valves. 

Action of the Large Arteries. — The large arteries 
have in their walls a yellow elastic tissue. When the 
blood is forced into them, they are stretched. As soon as 
the ventricle ceases to contract, 
and sends no more blood into 
the arteries, they "stretch back." 
We should not say contract, for 
it is simply an elastic reaction. 
As the artery reacts it presses on 
the blood, and hence the blood 
tries to escape in every possible 
way. It cannot go back, for it 
fills the pockets of the semilunar 
valves, and closes them with a 
click. A rapid wave is sent for- 
ward that gives the pulse, and a slower but still rapid 
stream flows along the arteries, through the pulmonary 
artery to the lungs, and through the aorta and its branches 
to all the other parts of the body. 




Nucleus 



sc'ated Fibers 



Fibers Joined 



Fig. 1 9. Plain (Unstriated) Muscu- 
lar Fibers from the Bladder. 



5o 



PHYSIOLOGY. 



The elastic reaction of the arteries thus helps to make 
steady the flow of blood, which is intermittent as it leaves 
the heart. The medium-sized arteries also have elastic 
tissue in their walls, and regulate the blood flow in the 
same way. 

Variation of the Amount of Blood Needed. — Each 
organ requires a supply of blood in proportion to its 
activity. An actively working organ, like the brain, de- 
mands much more blood than bone, practically inactive. 
Further, working tissues, such as the brain and muscles, 
need a great deal more blood while they are at work than 
when they are resting. An organ needing a constant large 
supply of blood might secure this by having a large artery. 
But how can the supply be regulated so that an organ 
may receive, now more, now less, according to its needs ? 

Plain Muscle Fibers in the Walls of the Arteries. — 

This is regulated by the medium-sized and small arteries 



Endothelium 



"■■> Nuclei 




Muscle Fiber 



Nucleus 



Fig. 20. Plain Muscle Fiber. Isolated and in Wall of Artery. 

leading to the parts. In the walls of these arteries are 
muscle fibers of a different kind from those of the skele- 



CIRCULATION OF THE BLOOD. 



5i 



ton. These fibers are spindle-shaped cells, as shown in 
Fig. 19, with a nucleus near the center, and do not have 
the cross-markings of the fibers of the skeletal muscles ; 
they are in consequence called nonstriated, smooth, or 
plain muscle fibers. They are arranged circularly in the 
walls of the arteries. These fibers have, in common with 
all muscle fibers, the power of shortening. When they 
shorten they reduce the size of the artery, and, there- 
fore, for the time, less blood can flow through the 
artery. When the muscle fibers cease to shorten, the 
artery widens, and allows more blood to pass through it. 



Illustration of the Action of Muscles in Arterial Walls. — To 

illustrate the action of the muscles in the walls of an artery, let the 
water run through a hose or large 
rubber tube. Now, if a row of per- 
sons take hold of this tube, the grip 
of their hands is like that of the 
muscles. When the hands tighten 
their grip, the caliber of the hose 
or tube is diminished, and less water 
is allowed to flow through it. When 
the hands relax, the tube, being 
elastic, allows more liquid to flow 
through it. 



Endothelium 



Internal Elastic 
Layer 




The Outer 
Coat 



Fig. 21. Coats of a Small Artery. 



Illustration of a Small Artery. 

— To represent a small artery, take 
a small, thin-walled rubber tube and 
wind a red thread around it. Now, 
if the thread could be made to 
shorten, it would diminish the cali- 
ber of the tube. The representation would be more exact if the thread 
were cut into many short pieces, and if each piece were thicker in 
the middle, and were then glued to the tube. If the whole were 
covered by a layer of tissue paper, the structure of the artery would be 
roughly represented. 



52 



PHYSIOLOGY. 



Plain and Striated Muscle Fibers Compared. — These plain mus- 
cle fibers are further like those of the skeletal muscles in that they are 
under the control of the nerves, but they are involuntary in their action. 




PIGMENT 
CELLS 



ARTERY 
Fig. 22. Part of Frog's Web (low magnifying power). 

We cannot interfere with the action of these muscles, no matter how 
strongly we may will to do so. Without our thinking about it, more 



CIRCULATION OF THE BLOOD. 



53 



blood goes to the muscles of the legs when we walk, more to the brain 
when we are studying, to the digestive organs after eating, etc. The 



Walls of Capillaries 



Tissues of Web 




• — "C ~ 



Fig. 23. Part of Frog's Web (highly magnified). 



plain muscle fibers shorten at a much slower rate than the striated 
fibers. They are also slower in relaxing. Since the plain muscles are 
usually found in the walls of hollow organs such as the heart, blood 



54 



PHYSIOLOGY. 



tubes, digestive tube, etc., they are sometimes called visceral muscles in 
distinction from the skeletal muscles. 

The Circulation of Blood in the Web of a Frog's Foot. — For this 
get a frog with a pale web. Take a piece of shingle six inches long 
and three inches wide. Cut a round hole, half an inch in diameter, 
near one end of it. Wrap the frog in a wet cloth, with one leg project- 
ing, and tie it, thus wrapped, to the shingle. Tie threads around two 
of the toes, and stretch the web, but not too tightly, over the hole. 
Keep the web moist. Place the shingle firmly on the stage of a micro- 
scope. Examine first with a low power. The large tubes which grow 
smaller by subdivision are arteries. The large tubes which are 
formed by the union of smaller ones are 
the veins. The finer tubes, forming a net- 
work in every direction, are the capillaries. 
They receive the blood from the arteries 
and pass it on to the veins. 

Put on a higher power, a one-fifth or 
one-sixth objective. It may now be seen 
that the colored corpuscles float more in 
the center of the stream, and with a steady 
motion, while the colorless corpuscles keep 
close to the walls of the capillary, and seem 
to adhere to them, advancing with a hesi- 
tant motion, seeming to roll along against 
the wall of the capillary. 

Close your eyes for a moment, and re- 
flect that in all the active tissues of your 
body — for example, the muscles, brain, and 
digestive organs — there is a similar net- 
work of fine tubes with a current of blood 
running through them. The current is not so rapid as it seems, for the 
microscope magnifies the rate of flow as well as the size of the cor- 
puscles. The blood really is moving slowly in the capillaries, and it is 
very important that it should be so, for in the capillaries the work of 
the blood is done. Part of the liquid of the blood soaks through the 
thin walls of the capillaries, and nourishes the surrounding tissues. All 
the other parts of the circulatory system exist for the purpose of send- 
ing a continuous, slow, and steady stream of blood through th« 
capillaries. (See pages 72 and 73.) 




Fig. 24. Capillary Blood 
Tubes of Muscle. 



CIRCULATION OF THE BLOOD. 



55 



Vein 



Connective (rg 

Tissue 



Artery 




Coat 



Fig. 25. 



Cross-section of Small Artery 
and Vein. 



The Blood Flow in the Capillaries. — The arteries 

divide and subdivide, and become capillaries, which have 

connecting branches, form- 
ing a close network of tiny 
thin-walled tubes. These 
penetrate nearly every tis- 
sue of the body. The blood 
cannot do its full work till it 
is in the tissues, and to reach 
the tissues it must soak 
through the walls of the 
capillaries. The work of 
the heart and arteries is to 
keep a steady flow of blood 

through the capillaries, that the tissues may be constantly 

supplied. 

How is it that the jerky action of the heart, at each 

contraction sending a jet of 

blood into the arteries, — 

shown by a spurt when an 

artery is severed, and also 

indicated by the intermit- 
tent pulse, — how is this 

intermittent flow converted 

into the steady, uniform 

current that we have seen 

in the capillaries ? 

Experiments illustrating the 

Blood FlOW in the Capillaries. — Longitudinal Section 

A few experiments may make this Fig. 26. Capillaries, composed of a singla 
matter more clear. la y er ° f cells. 

Material : — I. A common rubber syringe. 

2. A glass tube three feet long and seven sixteenths of an inch 
outside diameter. 



Surface View 




$6 PHYSIOLOGY. 

3. Four inches of the same size glass tubing, for making connec- 
tions. 

4. Several nozzles, made of the same size glass tubing, all fine, but 
of varying degrees of fineness. 

5. India-rubber tubing, twelve feet, three eighths of an inch inside 
diameter. This should be black, pure gum, rubber which is more 
highly elastic than the other kinds. 

6. Three feet of rubber tubing, same size as above. 

7. Four inches of white rubber tubing, same size as above, for 
making connections. 

In all the experiments, have one of the students assist by holding 
the outlet tube, so that (1) all the members of the class may see the 
stream, and (2) that the stream may be suitably directed, as into a pail 
or sink. 

Count aloud, to mark the exact time of each compression of the 
bulb, so the students can compare this with the time and duration of 
the jets of water. 

Be very careful to use perfectly clean water, as any fine particles of 
sediment drawn into the tube are likely to clog the fine outlet of the 
nozzle. And it is well to take the further precaution not to let the 
supply tube touch the bottom of the water-supply dish, as some fine 
sediment may get in in spite of previous care. 

Experiment i. — Remove the nozzle of the syringe, and put in its 
place the long glass tube. Work the syringe, and note that the jet is 
jerky, following each contraction of the bulb. 

Experiment 2. — Substitute the rubber tube, three feet long, for 
the glass tube. On working the bulb the stream will be found inter- 
mittent. 

Experiment 3. — Take off the rubber tube and replace the glass 
tube, adding the nozzle. Here the pressure will be so great that it is 
likely to push off the nozzle unless the assistant holds it firmly. It 
could be tied on, but this takes more time. On working the bulb, 
greater effort must be made on account of the resistance caused by the 
narrower outlet. 

Experiment 4. — Once more substitute the rubber tube, this time 
with a glass nozzle in its end. Now, on working the bulb, resistance 
will be felt, and the stream will be constant, or nearly so, and will con- 
tinue for some time when the bulb is no longer worked. This is be- 
cause the rubber has been stretched, chiefly laterally, and is now 



CIRCULATION OF THE BLOOD. 



57 



" stretching back." That is, by the elastic reaction of the rubber tube 
the jerky action of the bulb is converted into the steady flow that we 
see. In the first experiment we had a rigid tube and practically no 
resistance. In the second, although the tube was elastic, there was no 
resistance, so the elasticity was not brought into play. In the third, 
there was resistance, but the tube was inelastic. In the fourth, the 
resistance brought into play the elasticity of the rubber tube, and the 
elastic reaction of the tube continues (so to speak) the action of the bulb 
between two successive strokes. In this experiment the pulse can be 
felt in the tube. 

The Veins. — The capillaries, after penetrating the tis- 
sues, reunite to form small veins, which in turn reunite 
to form larger ones, till finally two great veins, the caval 
veins, precaval and postcaval, return the blood to the 
heart. The veins, like the arteries, are smooth inside and 
elastic (though less elastic than the arteries). They are 
thinner than the arteries, and, in consequence, collapse 
when the blood flows out of them, whereas the larger 
arteries stand open, after they are emptied of blood. 

The Valves in the Veins. — The only valves in the arte- 
ries are those which we have seen at the beginning of the 
aorta and pulmonary artery. 
Many of the veins have 
similar pocket-like valves, 
though less strong than 
those of the arteries. They 
are usually in pairs, but some- 
times single or in threes. It 
is important to note that they 
all have the mouths of the 
pockets toward the heart, so 
that the blood flows freely 
toward the heart, but is prevented from flowing the other 
way on account of the filling of the valves by the reflow 




Vein laid 
open 



CAI7 



krKy 



Open Shut 

Fig. 27. Venous Valves. 



58 PHYSIOLOGY. 

of the blood stream. When the blood is flowing through 
the veins toward the heart the valves lie against the walls 
of the veins. 

The valves are most numerous in the medium-sized veins, 
and especially in the veins of the extremities ; more abun- 
dant in the leg than in the arm. Valves are absent from the 
caval and some other veins, and from the very small veins. 

Illustration of Venous Valves. — Make a cloth tube (or take the 
lining of a boy 1 s coat sleeve) and sew three patch-pockets on the in- 
side, in a circle, i.e. with edges touching each other. Make the pockets 
a little "full." Pour sand, shot, or grain through the sleeve first in 
one direction and then in the Other. 

Evidences of Valves in our Veins. — With the forefinger stroke 
one of the veins on the hand or wrist toward the tips of the fingers. 
The veins swell out. The blood meets resistance in the valves of the 
vein. Their location may be determined by their bulging out during 
the experiment. 

Stroke a vein. toward the body, and the blood is pushed along with- 
out resistance. 

Let the left hand hang by the side. Note the large vein along the 
thumb side of the wrist. Place the tip of the second finger on this 
vein just above the base of the thumb. Now, while pressing firmly 
with the tip of the second finger, let the forefinger, with moderate 
pressure, stroke the vein up the wrist. It may be seen that the blood 
is pushed on freely, but comes back only part way. It stops where it 
reaches the valves, filling the vein full to this point, but leaving it col- 
lapsed beyond, as shown by the groove. Remove the second finger, 
and the vein immediately fills from the side nearer the tip of the fingers. 

These experiments show that the blood in the veins moves freely 
toward the body, but cannot flow outward to the extremities. 

Dissection of the Valves in a Vein. — The valves may be seen by 
dissecting out the jugular vein (or any other large superficial vein) of a 
cat, dog, or rabbit. Split the vein and pin it out on a board. 

Effect of Pressure on the Veins. — Since the valves in 
the veins open toward the heart, any intermittent pressure 
on the veins helps to push the blood on toward the heart 



CIRCULATION OF THE BLOOD. 59 

The valves are most numerous in the superficial veins and 
those of the muscles. The pressure of the muscles during 
their action (thickening while shortening) produces pres- 
sure on the veins ; and as the muscles act for a short time 
only, and then relax, this alternate compression and release 
aids very considerably in moving the blood on toward the 
heart. It is worthy of remark that this effect ' is more 
pronounced at the time the muscles need the most active 
circulation ; namely when they are in action, and are using 
the most blood. The heart has power enough to pump 
the blood clear around from each ventricle to the auricle 
of the other side of the heart ; but this outside aid comes 
in good play to relieve the heart at a time when it has an 
unusual amount of work to do, as when one is using a 
large number of muscles vigorously. 

" Every active muscle is a throbbing heart, squeezing 
its blood tubes empty while in motion, and relaxing so 
as to allow them to fill up anew." 

Rate of Blood Flow in the Arteries, Capillaries, and 
Veins. — The blood flows most rapidly in the arteries, 
slowest in the capillaries. Why is this ? 

When an artery divides, the two branches taken together 
are larger than the one artery that divided to form them. 
Stated more exactly, the sum of the areas of the cross- 
sections of the branches is greater than the area of the 
cross-section before branching. Hence as the blood flows 
on it is continually entering wider and wider channels ; 
and we are told that the united cross-section of all the 
capillaries fed by the aorta is several hundred times that 
of the aorta itself. 

The Flow of the Blood compared with the Current of 
a Stream. — If we walk along a stream, we see that the 



6o 



PHYSIOLOGY. 



channel varies considerably in width and depth. Where 
the channel is large, whether from increased width or depth, 
there the current is slower, but wherever the channel is 
reduced, the current is more rapid. So the stream in 
the relatively narrow artery is swift. In the capillaries, 



Pulmonary Vein - 



Left Auricle 



Left Ventricle 



Pulmonary Artery 
Lymph Vein 



Aorta 



Digestive Tube 




Fig. 28. Plan of Circulation. (Dorsal View.) 



although any individual channel is small, these channels 
all together are wide ; the result is the same whether a 
river widens out into a single lake, or divides into a great 
number of channels running past innumerable islands. 



CIRCULATION OF THE BLOOD. 6l 

All the tissues of the body may be regarded as so many 
islands lying between the capillary streams. 

The Blood Flow in the Veins. — When the blood re- 
collects in the veins it is entering narrower channels, and 
its rate is quickened ; but as the veins are wider than the 
arteries, the stream does not enter the heart with the veloc- 
ity with which it left that organ. The veins hold more 
blood than the arteries, and in dissecting the cat or rabbit 
it will be noticed that the arteries are emptied of blood; 
that the tissues of most of the organs are fairly free from 
blood; but that the great veins, such as the caval veins, 
are full. 

Blood Tubes compared to Two Funnels. — If the blood 
tubes leaving the heart could all be united, they would be 
best represented by a funnel with its tube connected with 
the heart. If another funnel were placed with its mouth 
to the mouth of the first, their point of union, the widest 
point, would represent the capillaries ; and if the second 
funnel had a wider tube than the first, it would fairly rep- 
resent the veins which return the blood to the heart. 

Nourishment of the Walls of the Heart and Blood 
Tubes. — The cardiac (coronary) arteries spring from the 
aorta just above the semilunar valves, and send blood into 
the muscular walls of the heart ; and these arteries, like 
others, divide, forming capillaries, through which the heart 
muscle is nourished. The cardiac veins return the blood 
to the right auricle. 

Influence of Gravity on Circulation. — Although the 
heart pumps the blood around through the body inde- 
pendent of the force of gravity, yet the circulation is influ- 
enced by this force. For instance, a person who has 



62 PHYSIOLOGY. 

fainted should be laid flat on his back, that the heart may- 
more easily drive blood to the brain. Many persons go to 
sleep more readily while sitting than while lying down. 
A sore hand feels less pain if held up, as in a sling, than 
when hanging by the side, and a sprained ankle does 
better rested on a chair, as less blood flows to it. Nearly 
every one has noted the pain following the pressure of 
blood when a sore hand, or foot, is suddenly lowered. 

Experiments illustrating the Effect of Gravity on Circulation. — 

Let all the pupils in the class stand. Let one arm hang freely by the 
side. Hold the other arm straight up as far as the clothing will readily 
permit. Observe : — 

i. The difference in the color of the two hands. 

2. The difference in fullness, both in the feeling of fullness and in 
the prominence of the veins. 

3. The difference in temperature; place the backs of the hands 
against the cheeks. 

The position largely determines the amount of blood in the hand, and 
the amount of blood determines the temperature, the size, and the color. 

The Heart Beat and the Pulse. — 1. The heart beat, felt at the left 
of the breast bone. 

2. The pulse, felt at the wrist and at various parts of the body. 
Perhaps the most convenient place to study it is at the temple. Lay 
the forefinger lightly along the cheek just in front of the ear. Count 
the pulsations for a minute. 

Let one or two pupils who are quick at figures step to the blackboard 
and put down the number of pulsations of each pupil, and divide by the 
number thus reporting, to get the average. 

1 . Let all in the class count the pulse while sitting. Probably it 
will be best to discard the first trial, as there are likely to be several 
failures from one cause or another. Then, too, there is usually a slight 
excitement at the beginning of a wholly new experiment. Get the 
average of the class. 

2. Find the pulse while sitting ; rise quickly, and immediately begin 
to count the pulse. Compare with the pulse as taken while sitting. 

3. Compare the pulse before and after meals. 



CIRCULATION OF THE BLOOD. 63 

Summary. — 1. The heart beats about seventy-two times a minute. 

2. The pulse is a wave running along an artery. 

3. The pulse varies with age, health, food, etc. 

4. The heart has two main cavities, one in each half of the heart, 
and two independent streams are flowing through it. 

5. Valves allow the blood to flow through the heart in one direc- 
tion, but prevent a reversal of the current. 

6. The heart is a hollow muscle, and by contraction forces the 
blood out into the arteries. 

7. The heart works rather less than half the time. 

8. The large arteries, by elastic reaction, push the blood on while 
the heart is resting. 

9. Circular muscle fibers in the walls of the medium-sized arteries 
regulate the blood supply to the organs. 

10. In the arteries the blood flow is rapid and intermittent, in the 
capillaries slow and constant. 

11. The thin walls of the capillaries allow the liquid part of the 
blood to soak out and nourish the tissues, and to soak back into the 
capillaries bearing waste matter. 

12. The veins are thin walled, and collapse when empty, while the 
arteries are thick walled, and stand open when empty of blood. 

13. Arteries carry blood from the heart, while veins carry it toward 
the heart. 

14. The veins have valves which allow the blood to pass toward the 
heart, but not away from it. 

15. Any intermittent pressure on the veins aids the blood flow. 

16. The blood flow is most rapid in the arteries, slower in the veins, 
slowest in the capillaries. 

17. Gravity influences circulation. 

Questions. — 1 . Why do the large arteries lie deep ? 

2. In which direction should the limbs be stroked to promote cir- 
culation ? 

3. How does slapping the hands around the body warm the 
fingers ? 

4. How can a horse or a cow be comfortable with the head down 
for a long time ? 

5. Why are the walls of the left ventricle thicker than those of the 
right ? 



CHAPTER V. 

CONTROL OF CIRCULATION. — THE BLOOD AND 
THE LYMPH. 

The Effect of the Emotions on Circulation. — In our 

every-day experience we have evidence of the control of 
the heart and blood tubes by the nervous system. We know 
that certain emotions affect the circulation of the blood 
and produce blushing and pallor. Certain emotions may 
also quicken or retard the action of the heart. Excessive 
grief or joy has produced sudden death by stopping the 
beat of the heart. 

Let us look a little more closely at that part of the 
nervous system that has such intimate relation to the 
blood system. 

The Rhythmic Action of the Heart. — In the first 
place, the action of the heart is automatic. The heart of 
the frog continues to beat a long time after it is removed 
from the body. This is regarded by many as due to the 
action of certain ganglia imbedded in the walls of the 
heart, especially in the auricles ; while others say that 
since the ventricle, in which no ganglia have been found, 
may beat independently of the auricles, rhythmic contrac- 
tion is characteristic of heart muscle, and that we are, at 
present, unable to explain it. 

But while the impulses that originate the action of the 
heart arise within the heart itself, still the beat of the heart 
is constantly modified by nerve impulses reaching it from 
without. 

64 






Carotid Plexus 



Middle Cervical Ganglion 



Pharyngeal Branches 



Deep Cardiac Plexus 

— - Superficial Cardiac Plexus 




Aortic Plexus 



Lumbar Ganglia 



Fig. 29. Vertical Section of Body, showing- Sympathetic Nerves and Ganglia of Right 
Side and their Connection with the Cerebro-splnal Nerves. 



66 



PHYSIOLOGY. 



Sources of the Heart's Nerve Supply. —The heart re- 
ceives'its nerves from two sources, the sympathetic system 
and the vagus (or pneumogastric) nerves. 

The Sympathetic Nervous System. — The sympathetic 
nervous system consists of two rows of ganglia in the body 
cavity, one along each side 

Of the Spinal Column, re- Sympathetic Nerve Chains 

ceiving branches from the 
spinal nerves, and sending 
branches to all the 
internal organs of 
the body, — the 
heart and lungs in 
the thorax, and the 
stomach, intestines, and the 
other organs of the abdomi- 
nal cavity. In many places 
these nerves form a thick 
network called a plexus. 

One very large plexus is on the dorsal surface of the 

stomach, and is called 
Spinaicord the solar plexus. 



Dorsal Root , 
Spinal Nerve 
Ventral Root 




Fig. 30. Relation of Spinal Cord and 
Sympathetic Nervous System (Diagram). 




The Vagus Nerves. 

— The vagus nerves 
are a pair of the cranial 
nerves arising from the 
sides of the spinal bulb ; 
and passing downward, 
they give branches to 
the pharynx, the gullet, 
the stomach, the larynx, the windpipe, the lungs, and the 
heart. Now, whatever other function the vagus nerves 



Sympathetic. 
Ganglion 



Fig. 31. Ideal Cross-section of the Nervous 
System. (After Landois and Stirling.) 



CONTROL OF THE CIRCULATION. 



67 



may have, they seem to have the power of retarding, or 
stopping altogether, the beat of the heart ; and stimulation 
of the vagus nerves may make the heart pause in a relaxed 
condition. Other nerves may quicken the heart beat, but 
the vagi are regarded as a brake on the heart's action. 

Inhibition. — This is a case of inhibition. It is well 
known that a severe blow over the stomach may cause one 
to faint by stopping the heart. This 
is due to reflex inhibition of the heart. 
The blow sends a nerve impulse by 
fibers of the sympathetic system to 
the center in the spinal bulb, and 
thence an impulse is taken by the 
vagus nerves to stop the heart. 

Vaso-constrictor Nerves. — In an 
experiment with the rabbit's 
ear it has been shown that 
stimulating the sympathetic 
nerve in the neck causes the 
ear to become pale. This is 
due to the constriction of the 
arteries of the ear, because 
the nerves have made the 
muscle fibers of these arteries 
shorten. Such nerve fibers 
are called constrictors, or vaso-con- 
strictors. They run in the sympa- 
thetic nerve, but have their origin 
and center in the spinal bulb. 

Vaso-dilator Nerves. — Other fibers 
may cause the opposite effect, namely, dilation, and are 
therefore called vaso-dilators. Examples of these may be 



Lungs 



Heart 



Liver 



Stomach 




Fig. 32. 



Diagram of Vagus 
Nerve. 



68 PHYSIOLOGY. 

found running to the arteries of the limbs. When the 
muscles of any organ, say the legs, act, they need a greater 
supply of blood. Now, at the same time that nerve im- 
pulses are sent to' the muscles of the legs to make the 
muscles shorten, impulses are sent along other fibers of 
the same nerves to make the arteries dilate, and allow 
more blood to flow to these muscles. 

Vaso-motor Nerves. — The vaso-constrictor and the 
vaso-dilator nerves taken together are called vaso-motor 
nerves. 

Centers of Control of . Circulation. — The centers of 
control of the blood tubes are in the cerebro-spinal nervous 
system. There is no Evidence that the sympathetic gan- 
glia are centers of reflex action. 

Blushing. — How is it that the face sometimes flushes 
so suddenly ? Because of some emotion, you say. But 
how does the emotion bring this about ? We have already 
learned about the muscles in the wall of the arteries. We 
are now prepared to understand that in the normal condi- 
tion nervous impulses are acting on these muscles, keeping 
them partly shortened, and so keeping the arteries of a 
moderate size. Under the influence of certain emotions, 
the caliber of the arteries is suddenly enlarged, and hence 
the change in color. 

The Regulation of the Size of the Arteries. — Through 
the sympathetic system the blood supply of all the organs 
of the body is regulated. Any organ needing more blood 
sends a message (nerve impulse) to some nerve center, and 
in response nerve impulses are sent to the muscle fibers of 
the supplying artery, and the amount of blood sent to that 
organ is regulated. For instance, a piece of ice is laid 



CONTROL OF THE CIRCULATION: 



6 9 



upon the skin of the hand. The part becomes pale, as 
the arteries have become narrowed. If this action be con- 
tinued, there may set in a decided reaction, and the part 
become more red than usual, when the reaction has 
widened the artery more than it was 
before the constriction. 

Effect of Exercise on the Size of the 
Arteries. — As there is only a certain 
amount of blood in the body, it is evi- 
dent that if one organ receives 
an extra supply, some other Sympathetic 
organ or organs must, for the Ganglions 
time, receive less. For in- 
stance, one begins to walk vigorously. 
The large muscles of the lower limbs 
and trunk become active, and they need 
more blood. They therefore send mes- 
sages to some nerve center (probably in 
the spinal cord), and by reflex action the 
arteries supplying the lower limbs are 
widened, and these muscles receive more 
blood. But these muscles make up a 
very considerable part of the weight and 
bulk of the body. While in action they 
take the lion's share of the blood. The 
brain, at such a time, would receive less, 
and it would be folly to expect the brain 
to work at its full capacity while the 
blood was called away to other organs. 

Regulation of the Effects of Exercise. — When we ex- 
ercise vigorously, the heart beats faster, and this of itself 
would tend to increase the blood supply to all organs. 




Fig. 33. Ventral View 
of Spinal Cord with 
Sympathetic Gang- 
lions of One Side. 



70 PHYSIOLOGY. 

But this mechanism for widening the channel leading to 
the working organs, while the arteries to the other organs 
are made smaller, or at least are not enlarged, solves the 
problem of supplying each part according to a greatly 
varying need, while not sending too much to a part not 
needing it. 

EFFECTS OF ALCOHOL ON THE CIRCULATION. 

The continued use of alcoholic liquors frequently causes 
what is known as " fatty degeneration " of the heart. 
The muscle cells are more or less replaced by fatty tissue, 
thus greatly weakening the heart. Experiments show 
that the first effect of alcohol on the heart is to weaken 
the force of the beat, though the rate is usually quickened. 
This indicates a deadening effect, such as is often seen in 
disease. Frequently the approach of death is indicated 
by a quickened but enfeebled heart-beat. 

"The warm and flushed condition of the skin which 
follows the drinking of alcoholic fluids is probably, in a 
similar manner, the result of an inhibition of that part 
of the vaso-motor center which governs the cutaneous 
arteries." — Foster. 

The control of the muscles in the walls of the arteries 
being thus interfered with, the circular muscles are no 
longer made to shorten, and the artery dilates, thus allow- 
ing more blood to flow into it. 

We may thus account for the flushing of the skin of the 
face, which in many individuals quickly betrays indulgence 
in alcoholic drink. If this flushing is too often repeated, 
the arteries gradually " lose tone," and the condition be- 
comes permanent. The circulation in the whites of the 
eyes may be affected, making them "bloodshot." 



CONTROL OF THE CIRCULATION'. 7 J 

Similar congestion occurs in the mucous membrane of 
the stomach from the presence of alcohol, which may 
become a permanent inflammation followed in time by 
very extensive changes in appearance and function. It 
is said that most of the alcohol swallowed is absorbed 
directly from the stomach, and hence the intestines are 
not so directly affected. 

Good authorities state that alcohol arrests the develop- 
ment of the corpuscles. It diminishes the size, alters the 
form, and reduces the number of the corpuscles. Since 
the work of the blood corpuscles is so important this 
reduction in their number and efficiency must very 
appreciably affect the nutrition of the body as a whole. 
When the blood is " out of order" the body is out of order. 

The Blood. — The blood is composed of a clear liquid, 
the plasma, and the blood cells, or corpuscles. In a drop 
of blood under the microscope the plasma occupies the 
clear spaces between the corpuscles. The corpuscles 
make up one third of the bulk of the blood, and the 
plasma two thirds. 

Microscopic Examination of the Blood. — To get a drop of blood 
from the finger, wind a cord around the finger, beginning at the base, 
drawing the cord moderately tight, until the last joint is reached. By 
this time the end of the finger is usually well distended with blood. 
With a clean needle make a quick, sharp, light puncture near the base 
of the nail ; this ordinarily brings a small amount of blood. Put a 
small drop on each of several slides and quickly cover with coverslips. 
Examine with a high power. 

The Colored Corpuscles. — These are often called the 
red corpuscles. But while in the mass they give the 
blood a red appearance, individually they are faint yellow- 
ish red. In shape they are seen to be circular disks, hol- 
lowed on each side like a sunken biscuit. As they are 



72 PHYSIOLOGY. 

hollowed on both sides they are more accurately described 
as biconcave. These corpuscles tend to gather side by 
side, in rolls, like coins. They are cells without nuclei. 

The Colorless Corpuscles. — In the open spaces be- 
tween the rolls of colored corpuscles may occasionally 
be found some spherical corpuscles. They are usually 



White Corpuscles 




HIGHLY MAGNIFIED 



Red Corpuscles 
in Rolls 



White Corpuscle 



MODERATELY MAGNIFIED 
Fig. 34. Red and White Corpuscles of the Blood. 

called the white corpuscles, but are better designated as 
the colorless corpuscles, since the others have only a slight 
color, and these have none. They usually have a dotted 
appearance. It is not so easy to distinguish the two kinds 
of corpuscles as it is in the case of the frog's blood, for the 
two kinds are more nearly of the same size in the human 



CONTROL OF THE CIRCULATION. 71 

blood ; and, further, when the colored corpuscles of human 
blood are seen flatwise they present a circular outline, while 
the frog's colored corpuscles are elliptical. But with a 
little study the two may be distinguished. As in the frog's 
blood, the colorless corpuscles have ameboid movements, 
though they are not very marked unless the blood be 
warmed to about the temperature of the human body. 

Flexibility and Elasticity of the Corpuscles. — It will 
be well here to examine again the frog's web. (See p. 54.) 
It will occasionally be seen that when one of the colored 
corpuscles is pressed against an angle at the forking of 
the blood stream, it is sometimes bent, and that as soon as 
the pressure is discontinued the corpuscle springs back to 
its former shape, showing that it is elastic. 

Frog's Blood. — A drop of frog's blood, mounted as the human blood 
was, will be helpful, as there is a very decided difference in the size and 
shape of the colored and colorless corpuscles. Further, the colorless 
corpuscles of the frog will show ameboid movements, i.e. slow changes 
of form, if watched a while. 

The Plasma. — The plasma consists chiefly of water, 
having in solution various salts, including common salt ; 
it also contains the nourishing materials for the tissues. 
These nourishing materials, obtained from the food by 
digestion, consist chiefly of proteids, fats, and sugar. The 
plasma also contains waste matters, from the working 
tissues, on their way out of the body. How the food is pre- 
pared for the building of tissue, and how the waste matter 
is removed from the body, we shall study a little later. 

The Color of Blood. — The difference in color of an in- 
dividual corpuscle and the blood in the mass may be better 
understood by comparing it with something that we see 
more frequently. A tumbler of currant jelly has a rich, 



74 PHYSIOLOGY. 

red color, but a thin layer of the same jelly, as when one 
takes a spoonful on a plate, has a pale color, more yellow- 
ish. The colorless plasma with the colored bodies in it 
may be compared to a glass dish filled with cranberries 
and water. 

Hemoglobin. — The coloring matter in the blood, then, 
is wholly in the colored corpuscles. Examination of these 
corpuscles shows that their color is due to a substance 
called hemoglobin. There is a small amount of iron in 
the hemoglobin, and the presence of this small quantity 
of iron appears to be essential to give the blood its color. 
When we come to the study of respiration we shall see 
that the hemoglobin in the corpuscles is the chief agent in 
picking up the oxygen from the air in the lungs and carry- 
ing it to the tissues in the body. 

The Coagulation of Blood. — When the blood escapes 
from its natural channels it usually changes from a liquid 
to a jelly-like condition. This is known as coagulation. 
It is due to the formation of threads of fibrin from the 
plasma. These threads of fibrin entangle and inclose the 
corpuscles, and the two constitute the clot, or coagulum, as 
it is more technically termed. The liquid that afterward 
separates from the clot is the serum, and differs from the 
plasma only in the removal of the fibrin, which is exceed- 
ingly small in quantity, though of great importance in its 
action. Many experiments have been made, and much 
has been written about the coagulation of the blood, and 
perhaps its real cause is not yet clear. But we know that 
the coagulation often serves to stop the flow of blood from 
wounds, and this is its main use. 

Fibrin. — If freshly drawn blood be stirred rapidly with 
a bundle of wires (perhaps the most convenient stirrer is 



CONTROL OF THE CIRCULATION-. 75 

a little roll of wire screen), there will soon collect on the 
wires a stringy substance. Thorough washing will soon 
leave this colorless. It is fibrin. If the stirring has been 
done thoroughly, the blood will no longer clot, no matter 
how long it may stand. 

Liquid Blood and Coagulated Blood. — The following 
scheme shows the difference between the liquid blood and 
the coagulated blood : — 



Plasma 



( Serum 
Liquid Blood j < Fibrin [ 
I Corpuscles 



Coagulated Blood. 



Amount of Blood. — The blood constitutes about one 
thirteenth of the weight of the body. In a body weighing 
one hundred and fifty pounds this would be about six 
quarts. 

Chemical Reaction of Blood. — Blood is alkaline. 

Specific Gravity of Blood. — Blood is somewhat heavier 
than water, owing to the salts and other matters dissolved 
in it. 

Quantity of Blood in Different Organs (approximately). 
— 1. One fourth is in the heart and the larger arteries 
and veins (including those of the lungs). 

2. One fourth in the liver. 

3. One fourth in the skeletal muscles. 

4. One fourth in the other organs. 

The Lymph Spaces. — We have seen that the capillaries 
have very thin walls. Through their walls part of the 
plasma of the blood soaks out, and is then called lymph. 
It passes into irregular cavities in the tissue called lymph 
spaces. Most of these lymph spaces are minute chinks or 



76 PHYSIOLOGY. 

crevices in the connective tissues of the different parts of 
the body. 

The Lymph Tubes. — Opening out of the lymph spaces 
are irregular passage ways called lymph capillaries, and 
these lymph capillaries are continuous with thin-walled 
tubes, the lymph tubes. These lymph tubes might be 
called the lymph veins, since they join still larger tubes 
closely set with valves, similar to those of the veins. But 
unlike the blood veins, the lymph veins do not gradually 
increase in size by confluence. They suddenly form a 
large tube, the receptacle of the chyle, beginning in the 
upper part of the abdomen. This tube soon narrows and 
passes through the diaphragm, close to the spinal column, 
and up along the column near the aorta, and empties into 
the veins of the neck at the junction of the left jugular 
and left subclavian veins. This tube is the thoracic duct, 
or the main lymph duct. It has numerous valves, and, 
like some of the smaller lymph veins, it presents a beaded 
appearance, due to the filling and bulging out of the valves. 
In the right side of the neck is a short right lymph duct 
which receives lymph from the right side of the head, 
neck, and thorax, and from the right arm. The lymph 
tubes, as a whole, are usually called the "lymphatics." 

Lymph Spaces in the Frog. — Tn dissecting the frog, the looseness 
of the skin is very noticeable. The large spaces under the skin are 
lymph spaces. Sometimes considerable lymph is found here, so that 
in holding up a frog the sagging of the skin from the weight of the 
lymph may be easily seen. 

Valves at the Mouth of the Lymph Tubes. — There 
are valves where these lymph ducts empty into the veins 
which prevent any reflow of liquid into the ducts, but allow 
the lymph to pass freely into the veins. 



CONTROL OF THE CIRCULATION. 77 

Muscle Fibers in the Walls of the Lymph Tubes. — 

There are plain muscle fibers in the walls of the lymph 
ducts 

Lymphatic Glands. — In its course the lymph passes 
through many kernel-like masses, the lymphatic glands. 
Lymph contains corpuscles which are considered identical 
with the colorless blood corpuscles/ It is thought that 
these corpuscles are formed in the lymphatic glands. 

The Flow of Lymph. — The flow of lymph is partly 
due to the blood pressure in the capillaries ; this pressure 
is caused by the heart. (In the frog there are two small 
hearts, — not, however, near the blood-pumping heart, - — 
and these pump the lymph along.) In our bodies the flow 
of lymph is largely aided by any pressure that may be 
brought to bear on the lymph veins ; for, on account of 
the valves, as in the blood veins, any pressure must push 
the liquid toward the heart. Thus the action of the mus- 
cles in the limbs, in the chest, in the abdomen, in the 
movements of breathing, and in the bending of the body, 
etc., all help in this flow, which is always, probably, very 
much slower than that in the blood veins. 

Relations of Blood Flow and Lymph Flow. — It will 

now be seen that while the blood leaves the left ventricle 
by one tube, the aorta, it returns to the right auricle, not 
merely by the two caval veins, but that a part of the blood 
{i.e. of the liquid part of it) does not return by blood veins, 
but having left the blood system proper through the thin 
walls of the capillaries, it is brought back to the heart by 
the lymph veins, which, however, join the blood veins just 
before they empty into the heart. There is, in other 
words, only one set of distributing tubes, but there are two 
sets of collecting or returning tubes. 



78 



PHYSIOLOGY. 



Left Jugular Vein 

Mouth of 
Lymph Vein 

LeftSubcIa-.. 
vian Vein *** 



— Right Lymph Vein 



Right Subclavian 
Vein 



Precaval Vein 




Blood Capillaries 



Fi(?- 35- Diagram of the Circulation of Blood and Lymph (Dorsal View). 



CONTROL OF THE CIRCULATION. 



79 



Lymph 



Capillary 



The Lymph. — Lymph is a clear liquid. (Chyle and 
the lacteals will be considered when we study digestion.) 
It is more watery than the blood plasma, but contains a 
share of all its nutritious substances. Lymph may be 
denned as "diluted blood minus red corpuscles" The 
blood proper never reaches the tissues. 

The Cells of the Body live in Lymph. — The cells 
of the tissues are bathed in the lymph which fills the 
spaces in the connective 
tissue (and we have seen 
that the connective tissue 
pervades nearly all the tis- 
sues of the body), as water 
may fill the spaces left 
between stones built into 
a wall. The cells get all 
their nourishment from the 
lymph, and into the lymph 
they throw all their waste 
matter. Each cell may be 
compared to an individual 
ameba, which lives in 
water, and takes all its 
nourishment from that 
water, and throws all its 
waste product into the 
same water. As water is 
the medium in which the 

ameba lives, so we may say lymph is the medium in 
which the cells of the body live. 

Cells of the Body Aquatic. — The cells of the body, 
i.e. all the active, working cells, may, therefore, be said 



Oxygen 



Food 




Other 
Wastes 



Fig. 36. Relation of Blood and Muscle. 
(Lymph being Middleman.) 



80 PHYSIOLOGY. 

to live an aquatic life, and only dead cells, as of hair, 
epidermis, etc., live in air. We might also say that not 
only the human body, but all animal life is aquatic. 

Importance of Lymph. — We can see that the move- 
ment and renewal of lymph are as necessary as the circu- 
lation of the blood itself ; is, in fact, the most important 
part of it. 

Lymph Cavities or Serous Cavities. — We have noticed 
the pericardial liquid. There is also a small quantity of 
similar liquid around the lungs in the pleural cavities, and 
in the abdominal or peritoneal cavity, around the digestive 
organs ; also in the cavities of the brain. The liquid in 
each case is lymph, and these cavities, often called serous 
cavities, are lymph cavities. They communicate with the 
lymph tubes. 

Dropsy. — In health the amount of the liquid in these 
cavities is small, but in certain disorders it may accumu- 
late. In general, such affections are called "dropsy." 
The lymph may also accumulate in the tissues of the 
extremities, causing swelling of the limbs. 

Variation in the Composition of Lymph. — It is evi- 
dent that the materials needed by the cells of the different 
tissues are not the same. So, as one tissue takes certain 
materials and another tissue others, it is clear that the 
lymph will not be of quite the same composition in the 
different parts of the body. This difference is further 
due to the difference in the waste products thrown out 
by the different cells. Hence the composition of the 
blood varies considerably in different regions. But the 
lymph from all the tissues unites with the blood from all 
the tissues in the right heart, and on their way to it in the 



CONTROL OF THE CIRCULATION. 8 1 

larger veins. So the constant slight differences in com- 
position of the blood and lymph in the various tissues are 
counterbalanced by the mingling of the currents from 
these various parts in the large arteries and veins. 




Fig. 36 A. Lymph Tubes of the Surface of the Arm. 

Massage. — A system of pressing, rubbing, and knead- 
ing the muscles is known as massage. It helps the flow 
of the blood and lymph, thus aiding in washing out the 
waste products from the muscles and other parts of the 
body that are to be reached by pressure. We have seen 
that one of the benefits of exercise is to promote the circu- 
lation of the blood and of the lymph, and so to help get 
rid of the waste matters that are produced by the activity 
of the various organs. Many invalids cannot take active 
exercise. So this passive exercise may very fairly take its 
place, and assist in the nutrition of the tissue by accelerat- 
ing the flow of blood and lymph, bringing new nourish- 
ment and carrying away wastes. For students who do 
not take sufficient exercise it is a good thing to rub the 
body thoroughly and briskly, not only after a bath, but 
often with the hands or with a dry towel. 

Transfusion of Blood. — Transfusion of blood is the transfer of 
blood from the blood tubes of one animal to those of another. Trans- 
fusion may be direct or immediate, as when the blood tubes of the 
two animals are connected by tubing so that the blood passes from one 
to the other without exposure to the air; in indirect or mediate trans- 
fusion the blood is first drawn into a receptacle. In indirect transfusion 
the blood is often defibrinated before transference. The blood may be 



82 PHYSIOLOGY. 

introduced either into an artery or a vein ; if into a vein it is sent in 
the direction of the natural flow, i.e. toward the heart ; if into an artery, 
in either direction. Soon after the discovery of the circulation of the 
blood the operation of transfusion began to be practiced, and high 
hopes were indulged in as to its value. But it was soon found to be 
attended by so much danger that it is now seldom used. It is resorted 
to (i) after great loss of blood, (2) after some forms of poisoning part 
of the blood is withdrawn and replaced by fresh blood, and (3) in 
certain disordered conditions of the blood. The chief dangers are (1) 
the introduction of air which forms minute bubbles and stops the blood- 
flow in the capillaries, (2) the introduction sometimes causes coagula- 
tion within the blood tubes, and (3) the serum of the introduced 
blood sometimes destroys the corpuscles of the blood to which it is 
added. In the earlier practice lamb's blood was employed, but now 
when transfusion is practiced on man only human blood is used. It 
has been found safer and better, after great loss of blood from hemor- 
rhage, to introduce a salt solution of about the natural degree of salt- 
ness of the blood ; this restores the normal volume of circulating liquid, 
and avoids most of the dangers except that of introducing air. The 
numerous fatal results of this operation have shown that it should not 
be resorted to except in cases of extreme necessity. 

The Spleen. — The function, or functions, of the spleen are not well 
understood. It is believed to have something to do with the renova- 
tion of the blood, perhaps forming colorless corpuscles and destroying 
colored corpuscles. At any rate, the physiologists generally call it a 
blood gland. It is unlike true glands in that it has no duct, and forms 
no secretion to be poured into any cavity, like the glands of excretion 
and secretion. It has been found, in the case of accidents to man, and 
by observations on the lower animals, that life may continue after this 
organ has been removed. 

For directions about stopping the flow of blood from 
wounds, see Chapter XXIII. and the books named below. 

Reading. — Prompt Aid to the Injured, Doty; Emer- 
gencies, Dulles ; Emergencies, Howe ; First Aid to the 
Injured, Lawless; First Aid to the Injured, Morton; First 
Aid in Illness and Injury, Pilcher ; Sickness and Accidents, 
Curran. 



CONTROL OF THE CIRCULATION. 83 

What other process keeps pace with the coursing of the 
blood through the body, being its running mate, so to 
speak ? 

Summary. — 1 . Blushing, and other variations in blood supply, are 
under the control of the sympathetic nervous system. 

2. The sympathetic nervous system consists of two rows of ganglia 
in the body cavity near the spinal column, with fibers running to the 
internal organs. It is also connected with the cerebro-spinal nervous 
system. 

3. The heart beat is automatic and rhythmic. 

4. The heart beat is regulated by the sympathetic nervous system 
and by the vagus nerves. 

5. The blood consists of a liquid, the plasma, in which float the 
colored and colorless corpuscles. 

6. When blood is shed it coagulates, tending to check its own 
escape. 

7. Lymph is like the blood diluted and lacking the colored cor- 
puscles. 

8. A set of lymph tubes conveys the lymph into the veins to join 
the flow toward the heart. 

9. In its course the lymph passes through the lymphatic glands. 

Questions. — 1. What makes the hands grow red and pufF up on 
sitting in a warm room after snow balling ? 

2. How is a mustard plaster effective ? 

3. Why does light exercise before retiring promote sleep ? 

4. Why are the feet often cold after studying ? 

5. How does the application of ice, or cold water, relieve headache ? 

6. Why should the clothing be changed after getting wet ? 

7. What is the meaning of humor, in the expressions a good- 
humored," " bad-humored " ? Have these expressions a real physio- 
logical significance ? 



CHAPTER VI. 



RESPIRATION. 



The Close Relation between Circulation and Respira- 
tion. — Is it not a very striking fact that we take one 
breath for every four heart beats? That whatever quick- 
ens the breathing also quickens the heart, so that the two 

always keep in al- 
most the same ratio ? 
Let us learn what 
are the many inti- 
mate relations of 
the blood pump and 
the air pump, the 
blood system and 
the air system, of 
Circulation and Res- 
piration. 

The Organs of 
Respiration. — 

i . The lungs and 
air tubes. 

2. The structures 
which increase and diminish the size of the chest, princi- 
pally the diaphragm, and the muscles acting on the ribs. 

The Parts of the Lungs. — i. The Air Vesicles, an 

immense number of small sacs, which communicate with 

8 4 




Fig- 37. The Trachea and Bronchial Tubes, showing 
Two Clusters (Alveoli)) of Air Vesicles. 



RESPIRATION. 



85 




1. Pulmonary Orifice 

2. Aortic Orifice 



3. Left Auriculo-Ventricular Orifice 

4. Right Auriculo-Ventricular Orifice 

The heavy black line between thf, heart and the liver represents the diaphragm 



Fig. 38. Front View of the Thorax. The Ribs and Sternum are represented in 
Relation to the Lungs, Heart, and other Internal Organs. 



86 



PHYSIOLOGY. 



the outer air by the bronchial twigs, the bronchi, and the 
trachea. 

2. The Pulmonary Capillaries, forming a thick network 
around and between the air sacs. These capillaries receive 
their blood from the pulmonary artery, and return it to the 
heart by the pulmonary veins. 

Elastic Tissue in the Lungs. — The air vesicles, with 
their supplying air tubes and their surrounding blood tubes, 
are bound together by elastic tissue, which fills up most of 
the intervening space. 

The Windpipe or Trachea. — The windpipe has in its 
walls C-shaped cartilages, with the open part of the C 
on the dorsal surface. These cartilages continue in the 
bronchi, and so on until in the smaller twigs they finally 
disappear. The cartilages are held together, and the 
dorsal gap of the cartilages (the gap would be like that of 
a series of horseshoes piled one on top of another) bridged, 
by tough fibrous tissue, with much elastic tissue, and 
with plain muscle fibers ; the plain muscle fibers are very 
abundant in the smaller air tubes. 

The Mucous Membrane. — The lining of the trachea 

is a mucous mem- 
brane. It pours 
out on its surface 
a substance some- 
what like white of 
Qgg, called mucus. 
This keeps the air 

Fig. 39. Ciliated Cells lining the Air Tubes (x 300). moistj and catcheg 

particles of dust that are in the inspired air. There is a 
constant slow current of mucus toward the throat, whence 
it is, from time to time, hawked up. 



Cilia 



Cell .. 



Nucleus 




RESPIRATION. 



87 



Cilia. — This current of mucus is caused by the cilia 
projecting from the lining cells of the trachea. They are 
little hairlike projections, in countless numbers, like a field 
of grass, each stalk having the power of bending back and 
forth, making a quick stroke toward the throat, then a 
slower recover stroke. Thus the united wavelike action 
of the myriads of lashing cilia paddles the mucus head- 
ward. It is a very common error to suppose that the cilia 
produce air currents. This is not their function, and it 
can readily be seen that they cannot create currents of air, 
as they are wholly submerged, like grass growing on the 
bottom of a shallow pond of slimy water. 

Location of Mucous Membrane. — All the cavities and 
passages in the body to which the air has access, such as 
the digestive and respiratory passages, etc., are lined by 
mucous membrane (not all 

Ciliated). Trachea 

The Pleura.— The out 
side of each 
lung is cov- 
ered by a thin 
adherent mem- 
brane, the pleu- 
ra, which com- 
pletely invests 
it, except at the root of 
the lung, where the bron- 
chus and blood tubes 
enter. Here the pleura 
turns toward and adheres to the inner wall of the chest, 
forming its lining (still called the pleura), and below passes 
over the anterior surface of the diaphragm. The lung is 



Pleural Space 
(Exaggerated) 



Chest Wall — 



A~~" Pleura 




Fig. 40. Diagram of the Lungs and Pleurae. 



88 PHYSIOLOGY. 

thus free, except at its root, where the air and blood tubes 
enter. A very small quantity of liquid moistens the con- 
tiguous surfaces of the pleurae on the outside of the lung 
and the inside of the chest wall, so they move easily one 
upon the other during respiration. As the lungs are 
always distended enough to fill the chest cavity, these two 
surfaces are always in contact. In pleurisy (inflammation 
of the pleurae) pain is felt in breathing from friction or 
adhesion of these surfaces. 

Important Facts concerning Respiration. — In study- 
ing respiration, let us constantly keep in mind these 
facts : — 

1. The lungs are highly elastic, and 

2. Highly porous, each air vesicle being in direct com- 
munication with the outer air by means of 

3. Air tubes that always stand open 

4. And are always moist internally. 

5. The pulmonary capillaries closely invest each air 
vesicle. 

6. The lungs are always expanded enough to fill all 
the space in the chest not occupied by other organs, and 

7. Freely movable, except at the place of entrance of 
the bronchi and blood tubes. 

8. The smooth, moist pleurae. 

The Diaphragm. — The diaphragm is a thin muscle 
making a complete partition between the abdominal cavity 
and the chest cavity. It is convex anteriorly, concave pos- 
teriorly ; its ventral border is attached to the inside of the 
chest wall about opposite the lower end of the breast bone, 
thence obliquely along the border of the ribs (as felt in 
front), and the dorsal attachment is posterior to the ventral 



RESPIRATION. 



8 9 



attachment. Its general position is shown in Figs. 38, 40, 
and 43. 

To show the Action of the Diaphragm and Lungs. — Material. — 
Bell jar with stopper, sheet of rubber large enough to cover the mouth 
of the jar, toy rubber balloon, cork (rubber preferred), glass tube, strong 
rubber band (such as boys use for sling shots), marble. 



Triangularis Stern 
Internal Mammary Vessels 



Left Phrenic 
Nerve 



Pleura 
Pulmonalis 

Pleura Costalis 




Mediastinum \ Sympathetic Nerve 

Thoracic Duct 



Vena Azygos Major ^ p osterior 
Pneumogastric Nerves 



Fig. 41- A Transverse Section of the Thorax, showing the Relative Position of the 
Viscera and Reflections of the Pleurae. 



Preparation. — Lay the marble on the center of the sheet of rub- 
ber, double the rubber over it, stretching the rubber strongly over the 
marble, and tie the marble firmly in its place. Stretch the sheet of 
rubber over the mouth of the jar with the projection made by the marble 
on the outside, and fasten with rubber band. Bore a hole in the cork, 



90 PHYSIOLOGY. 

and fix the glass tube snugly in it, so that the lower end of the tube will 
extend about half-way down the jar. Tie the balloon on the lower end 
of the glass tube. 

Experiment i. — Inflate the balloon. Consider that it requires 
some expenditure of energy to do this. When the mouth is taken away 
from the tube the balloon immediately collapses. 

Experiment 2. — Insert the balloon and tube into the jar, but do 
not cork, and repeat Experiment 1. The same results as before are 
noticed, and it will further be seen, or rather heard and felt, that when 
the balloon is inflated some air comes out of the jar around the tube, 
and when the balloon collapses air again enters the jar. 

Experiment 3. — Again inflate the balloon, and while it is inflated 
tightly cork the jar. If all the parts fit well, the balloon should now 
remain inflated. This may at first seem strange, as the mouth is taken 
away from the tube, and the tube left entirely open to the air. But it 
will be seen that to just the extent that the balloon contracts, so much 
more space is left in the jar outside the balloon. This means diminished 
pressure, and the pressure of the outer air presses the diaphragm up, 
and keeps the balloon partly distended, maintaining equilibrium. 

Experiment 4. — Pull the diaphragm down, using the marble as a 
handle. This shows the expansion of the lung by the pressure of the 
external air when more space is given by the depression of the dia- 
phragm. On releasing the diaphragm, it springs upward, and the 
balloon becomes reduced in size, driving out part of the air that was in 
it. This shows how expiration is accomplished, so far as the diaphragm 
is concerned. 

If a bell jar be not at hand, a lamp chimney or a quart bottle may be 
used, after cutting off the bottom, as follows : File a deep notch across 
near the bottom ; heat an iron rod, and apply the end of it to one end 
of the notch, and slowly draw the rod around to the other end of the 
notch (the rod may need to be reheated). After cracking off the bot- 
tom of the jar, file the edges so they will not cut the rubber. 

Let each pupil make a drawing, showing the position of the parts in 
inspiration and in expiration. 

Illustration of the Minute Anatomy of the Lung. — To illustrate 
the minute anatomy of the lung, take a rubber balloon, a glass tube, 
two rubber tubes, one dyed red, the other blue, a bag of netting, with 
one side dyed red and the other side blue. Tie the balloon on the end 
of the glass tube, slip the bag of netting over the balloon and tie it, 



RESPIRATION'. 9 1 

with the ends of the rubber tubes on the corresponding sides of the 
bag. Slip a short piece of the rubber tube on the end of the glass 
tube, and when the balloon is inflated shut the air in by means of a 

CILIA I i BRONCHIAL TUBE. 



Fig. 42. Minute Structure of the Lungs, showing Air Vesicles 
and Capillaries. 

pinchcock. The balloon represents an air vesicle, the glass tube a 
bronchial twig, the blue tube a subdivision of the pulmonary artery, 
the netting the capillaries around the vesicle, and the red tube one of 
the branches of the pulmonary veins. 

The Movements of Respiration. — The process of res- 
piration consists of two acts, inspiration and expiration. 

Two Active Forces in Inspiration. — In inspiration 
the principal active forces in the body are, first, the dia- 
phragm ; and, second, the muscles which elevate the ribs. 

Work of the Diaphragm in Inspiration. — The dia- 
phragm is a muscle, and when its fibers shorten, the dia- 
phragm is pulled down. In moving down it presses on 
the abdominal organs, and makes the abdomen protrude 
laterally and ventrally. This lowering of the diaphragm 
increases the space in the chest ; the air already in the 



92 PHYSIOLOGY. 

chest expands to fill this greater space. When expanded 
it exerts less pressure than before, and the air outside, 
having greater pressure, enters till equilibrium is produced. 
The air enters through the trachea, presses on the inside 
of the elastic lungs, and makes their bases extend, follow- 
ing the diaphragm in its descent. The bases of the lungs 
remain in contact with the upper surface of the diaphragm 
all the time. 



Increased Air 
Space 





Inspiration Expiration 

Fig. 43- Diagrammatic Sections of the Body in Inspiration and Expiration. 

Work of the Chest Walls in Inspiration. — Certain 
muscles of the chest wall elevate the ribs and breast bone. 
This act widens the chest, and the air, as before, presses 
in through the open trachea, and keeps the sides of the 
lungs in contact with the inner surfaces of the chest walls. 

Effort required in Depressing the Diaphragm. — 

Inspiration requires considerable effort, because the dia- 



RESPIRATION. 93 

phragm in its descent presses upon the elastic organs of 
the abdomen (stomach, liver^ etc.), and these organs, in 
turn, are pressed against the elastic walls of the abdomen. 
It is somewhat like pressing a pillow down into a rubber 
bag ; the pillow springs up as soon as the pressure is 
stopped, because of its own elasticity as well as that of the 
bag. Therefore, as soon as the diaphragm relaxes, the 
elastic walls of the abdomen retreat, and the abdominal 
organs rise to their former place. 

Effort Required in raising the Ribs. — When the ribs 
are elevated, the cartilages which connect the ventral ends 
of the bony parts of the ribs with the breast bone are 
slightly bent. When the muscles relax, the elasticity of 
the rib cartilages helps to bring the ribs back to their 
former position, thus reducing the chest to its former 
width. 

Expiration Easy. — Thus we see why expiration is easy ; 
in fact, " does itself " (in ordinary respiration) by elastic 
reactions. But inspiration is harder than it would be if it 
were not for the fact that the descent of the diaphragm 
meets resistance, and the ribs, in rising, have to overcome 
resistance in bending the costal cartilages, and in raising 
the weight of the chest walls and shoulders. 

Potential Energy stored in a Door Spring. — When 
one opens a door that has a spring to shut it, he has to 
expend more energy to open the door than he would if he 
did not have to bend (twist or compress) the spring at the 
same time. But no effort is needed to shut the door. The 
door was opened and shut at the same time ; i.e. when 
the door was opened force was stored in the spring (in the 
form of what is called potential energy), and this stored 
energy shuts the door while we pass on. We can better 



94 PHYSIOLOGY. 

afford to employ more energy while opening the door than 
to take the extra time to shut it. If, then, a door with such 
spring were fastened open, it might remain open for a long 
time. When released it flies shut. If one, in this case, 
asks, "Who shut the door?" the answer is, "The person 
who opened it." 

The Storing of Energy during Inspiration. — So in 

the act of inspiration we perform a double work in storing 
energy by which the expiration is performed without active 
muscular effort. 

Review of Forces of Respiration : — 

FORCES OF INSPIRATION. 

i. Depression of the diaphragm. 

2. Muscles elevating the ribs. 

3. Pressure of the external air. 

RESISTANCES TO INSPIRATION. 

i. Compression of the abdominal organs and stretching 
abdominal walls. 

2. Bending the rib cartilages and lifting the chest. 

3. Stretching the lungs. 

ELASTIC REACTIONS OF EXPIRATION. 

1. Elastic reaction of the abdominal walls and contents. 

2. Elastic reaction of the rib cartilages. 

3. Elastic reaction of the lungs. 

Forced Respiration. — Thus far we have been speaking 
of ordinary respiration. In forced respiration, as in shout- 
ing, many muscles are brought into play to expel the air 
rapidly and forcibly. In such an act as coughing there is 
vigorous action of the abdominal muscles. 



RESPIRATION'. 95 

Abdominal and Thoracic Respiration. — The main part 
of respiration is performed by the diaphragm, and the more 
common mode of respiration is therefore called abdominal 
or diaphragmatic respiration. In women of the civilized 
races respiration is more largely accomplished by the action 
of the thoracic muscles, and is called thoracic or costal res-: 
piration. In children the respiration is of the abdominal 
type. 

The Rate of Respiration. — The rate of respiration in 
the adult varies from sixteen to twenty-four per minute, 
the average being about seventeen times a minute ; about 
one respiration for every four heart beats. Light is favor- 
able to respiratory activity. The rate is affected by the 
position of the body, state of activity, temperature, diges- 
tion, emotions, age, disease, etc. Ordinary inspiration 
takes slightly less time than expiration. 

Modifications of Respiration. — Coughing is a forcible expiration, 
usually directed through the mouth, and for the purpose of getting rid 
of some foreign substance, or caused by irritation. In sneezing there is 
first a deep inspiration, and then the current of air is forced out, chiefly 
through the nose. Sneezing may be prevented by pressing firmly on 
the upper lip. Crying, laughing, sobbing, are modifications of respira- 
tion connected with certain emotions. Yawning and sighing are deeper 
breathings, caused by ennui, depressing emotions, or a deficient ventila- 
tion. Hiccuping is sudden inspiration, produced by spasmodic action 
of the diaphragm, accompanied by sudden closure of the glottis, and is 
often caused by some disorder of stomach digestion. Snoring is caused 
by breathing through the mouth and setting the soft palate into vibra- 
tion. Sniffing is sudden inspiration : the diaphragm is suddenly pulled 
down, the air in the nasal cavity is thus drawn downward, and the air 
we wish to test, or the odor we wish to inhale, is thus drawn into the 
upper nasal cavities ; whereas in ordinary inspiration most of the air 
passes along the lower part of the nasal passage. In hawking, the air 
is forced out through the narrowed passage between the root of the 
tongue and the soft palate to remove mucus. Gargling is forcing air up 



9 6 



PHYSIOLOGY. 



through liquid held between the tongue and the soft palate. Panting, 
whistling, blowing, spitting, sucking, and drinking are also modifica- 
tions of respiration. In case of choking it is well to hold the head for- 






"St" =3 

c3 CO 

CD 95 
CO 



COMPLEMENTS. AIR. 

120 CUBIC INCHES. 
AIR THAT CAN BE BUT SELDOM IS TAKEN IN. 



TIDAL AIR.— 20 to SO Cubic Inches Air Taken in 
and Sent out at Each Breath. 



RESERVE AIR. 

100 CUBIC INCHES. 
AIR THAT CAN BE BUT IS SELDOM DRIVEN OUT. 



RESIDUAL AIR. 

100 CUBIC INCHES. 
AIR THAT CANNOT BE DRIVEN OUT. 






5 ■« 



Fig. 44. Diagram of Lung Capacity. 

ward, and perhaps downward. A smart slap between the shoulders 
sometimes helps dislodge anything stuck in the throat, and it may be 
necessary, in addition, to hold a child with its head downward. 



RESPIRATION. 97 

Capacity of the Lungs. — Have the class stand, and each pupil raise 
his right hand. 

i . Tidal Air. — Let all breathe together, at the ordinary rate and 
depth, and let the hand rise about three inches during inspiration, and 
fall again during expiration. The amount of air taken in at an ordinary 
breath is from 20 to 30 cubic inches, or about a pint. This is called 
tidal air. 

2. Complemental Air. — As before, let the hand go up and down 
with the breathing, but at the end of the third inspiration, instead of 
stopping with the usual amount, keep on breathing in as much as pos- 
sible, letting the hand rise accordingly. This air that can be taken in 
above the ordinary breath is called the complemental air, and it is 
estimated to be, on the average, about 120 cubic inches. 

3. Reserve Air. — Begin as before, and at what would be the end 
of the third expiration continue to drive out as much air as possible, 
indicating the degree by correspondingly lowering the hand. This air 
that can be breathed out beyond the ordinary expiration is called the 
reserve air, and is reckoned at about 100 cubic inches. 

4. Residual Air. — The air cannot all be breathed out. The re- 
mainder is called the residual air, and is computed to be about 100 
cubic inches. 

The Vital Capacity. — All the air that can be breathed out after a 
full inspiration, i.e. the sum of the complemental, tidal, and reserve 
air, would be about 240 to 250 cubic inches, and is called the vital 
capacity. Of course these figures represent only the average of cer- 
tain experiments and observations. By practice any one can con- 
siderably increase his vital capacity. 

A Test of the Capacity of the Lungs. — A simple method of 
measuring these stages of respiration is to take a gallon bottle and 
first carefully graduate it to pints by pouring in water and marking on 
the outside with a file. Then invert the bottle in a trough of water, 
and inhale from it by means of a rubber tube. Or fill the bottle, in- 
vert in water, and exhale into it. 

Hygiene of Breathing. — Those persons who take con- 
stant exercise in the open air are likely not to suffer much 
from deficient respiration. But persons following seden- 



98 PHYSIOLOGY. 

tary occupations, such as that of the student, not calling 
for deep breathing (and often the air taken in is of poor 
quality), need to pay especial attention to the matter. 

Breathing through the Mouth. — We should breathe 
through the nose, and not through the mouth. The nasal 
passages are fitted for the introduction of the air (i) by 
being narrow, but of large area ; (2) by having their lining 
membranes richly supplied with blood; (3) by the abun- 
dant secretion of mucus by this membrane. The air, 
coming through this narrow channel, is warmed, and a 
large part of any dust it may contain is caught by the 
sticky mucus that covers all the walls of this passageway. 
If we breathe through the mouth (especially out of doors 
in cold weather), the air may not be sufficiently warmed 
before entering the lungs, and much more dust would be 
carried into the lungs. Then, too, the air has a drying 
effect on the throat, whereas the mucus of the nasal pas- 
sages will moisten the air as it enters. The cilia, which 
extend from most of the cells lining the respiratory pas- 
sages, are constantly causing the mucus to slowly flow 
toward the external opening, so a good share of the dust 
is gotten rid of. A further advantage of breathing through 
the nose is that we detect odors, and can thus judge of the 
quality of the air. 

Breathing and Circulation. — The fact has been noted 
that breathing directly aids the circulation of the blood. 
This is due to the way air pressure is made to affect the 
large veins. Breathing also may very considerably aid 
the flow of lymph. Every deep inspiration brings pres- 
sure to bear on the main lymph duct as the diaphragm 
descends. Every forced expiration has the same effect. 
We must keep in mind that the tissues are fed directly by 



RESPIRATION. 99 

the lymph that surrounds them ; that while the lymph is 
continually fed by the blood, there is not a great pressure 
given in this way. The lymph stream is largely depend- 
ent on the pressure of the surrounding organs. When 
one takes a good deal of muscular exercise the lymph is 
renewed with rapidity enough to supply the tissues with 
food, and to carry away their wastes. But in those who 
sit quiet a large share of the day, taking no more exercise 
than is necessary to take them to and from their places 
of business, the lymph becomes too nearly stagnant, the 
tissues are not well nourished, and the whole body suffers. 

Deep Breathing. — It is a grateful relief to the whole 
system to stand, stretch, inhale deeply and slowly several 
times, and to repeat this every hour or so. Every one en- 
gaged in office work or studying should form this habit, 
especially if he does not give an hour daily to exercise in 
a gymnasium, or otherwise. 

Respiratory Sounds. — During respiration sounds are 
produced by which the skilled physician can tell much as 
to the condition of the respiratory organs. 

The Control of Respiration. — Breathing is an involun- 
tary act. Still we can modify it. We can hold the breath 
for a time ; but it is stated that one cannot hold the breath 
Long enough to produce death by suffocation. 

The muscles of respiration are under the control of 
nerves. The center of respiratory control is believed to 
be in the lower portion of the spinal bulb. This respira- 
tory center is one of the most vital points in the body, for 
if it is destroyed, breathing is completely stopped, and 
death ensues. This center is affected by the condition of 
the blood. For instance, if the blood going to this center 
has not enough oxygen, the center hastens the process 



IOO PHYSIOLOGY. 

of breathing by nerve impulses sent to the muscles of 
respiration. 

The Control of the Diaphragm. — The diaphragm is 
under the control of the phrenic nerves, which arise from 
the third, fourth, and fifth cervical nerves. If the neck is 
broken above the point where these nerves are given off, 
death almost always immediately follows, because the con- 
nection of the respiratory center and the diaphragm is 
broken. 

Composition of Dry Air (by volume) : — 

Oxygen ... ........ 21.00 

Nitrogen 79.00 

Carbon Dioxid .04 

100.04 

Experiments illustrating the Chemistry of Respiration. — Ex- 
periment 1 . — If a piece of phosphorus be burned under a fruit jar 
inverted and with the mouth under water (for directions consult any 
chemistry), the oxygen will be consumed and water will enter part way 
to take its place. The remainder is nitrogen. 

Experiment 2. — If a burning taper be lowered into this nitrogen, 
the flame will be extinguished. 

Experiment 3. — If a chemical laboratory is at hand, some carbon 
dioxid should be generated and tested to show that it extinguishes 
flame. 

Experiment 4. — Lime water is the test of carbon dioxid, and may 
easily be prepared by putting a piece of quicklime the size of a hen's 
egg into a quart of water. 

Experiment 5. — Pour a little clear lime water into a jar contain- 
ing carbon dioxid, and on shaking the contents the lime water will be 
rendered milky. 

Experiment 6. — By means of a tube (a straw will serve) breathe 
through a small quantity of lime water to show. that there is carbon 
dioxid in the expired breath. 

Experiment 7. — If a jar be inverted over a lighted taper, the flame 
will soon be extinguished. Test the gas with lime water to see that 
carbon dioxid is produced by a burning candle. 



RESPIRATION. IOI 

Experiment 8. — By holding a clean, cold tumbler over a burning 
taper it will be seen that water vapor is produced by the burning. 

Experiment 9. — Breathing into a clean, cold tumbler shows that 
water is produced also in the process of respiration. 

Experiment 10. — A very brilliant experiment and one that is very 
instructive at this point is to burn a watch spring in oxygen. In this 
process the oxygen unites with the iron, forming iron oxid. 

Experiment ii. — If a piece of watch spring be placed in water, it 
will soon rust. Rust is also an iron oxid, only the process is slow, 
instead of rapid as in the case of combustion, and just as much heat is 
given off, but not much at any given instant. 

Experiment 12. — If a short piece of magnesium ribbon can be 
obtained, it may be burned in the presence of the class, though it is not 
well to look long at the excessively strong white light. 

Experiment 13. — Magnesium will also rust in water, forming a 
white rust, or magnesium oxid, as in burning. 

Experiment 14. — If a jar be filled with the slowly expired breath, 
capped tightly, and set in a warm place it will acquire a bad odor. 

Experiment 15. — Hold a thermometer at arm's length. It indi- 
cates the temperature of the air — of the air that you are breathing in. 
Breathe for a few minutes upon the bulb of the thermometer, and the 
fact is clearly shown that the air we breathe out is much warmer than 
the air that we breathe in. 

Experiment 16. — With a pair of bellows force the air of the room 
through a small quantity of lime water. By continuing this process a 
long time it may be shown that there is carbon dioxid in the air, but not 
nearly so much as in the expired breath. 

Result of Experiments. — These experiments show that 
breathed air has gained : — 

1.. Heat. 

2. Water vapor. 

3. Carbon dioxid. 

4. Waste products, or impurities, having no definite 
name, because not well known, highly putrescible, often 
called by the general name of "organic waste matter." 



102 



PHYSIOLOGY. 



IN 10,000 VOLUMES. 

(Represented by Large Square.) 

PER CENT. 



COMMON FRACTION 




AMOUNT OF CARBON 

DiOXID 

IN 

INSPIRED AIR. EXPIRED AIr! 



4 400 

(Small Square.) (Medium Square). 



.04 



2500 



4 



25 



20 100 

Fig. 45. Amount of Carbon Dioxid in Inspired and Expired Air. 

The Composition of Inspired and Expired Air. — 

Oxygen. Nitrogen. Carbon Dioxid. 
Inspired air . . . 21 79 .04 • 

Expired air . . . 16 79 4.00 



While the amount of nitrogen remains about the same, 
some oxygen has disappeared, and its place is taken by 
carbon dioxid, while the amount of carbon dioxid has in- 
creased a hundred-fold. 



RESPIRATION'. 



103 



Exchanges between the Air and the Blood in the 
Lungs. — Whatever the air coming from the lungs con- 
tains that was not in the air entering them, it has taken 
from the blood, and what the air has lost it has given to 
the blood. The air in the air vesicle is separated from the 



BRONCHIAL TUBE 



FROM PULMONARY ARTERY 



TO PULMONARY VEIN 




CORPUSCLES 
Fig. 46. Exchanges between the Air and the Blood in the Lungs. 

blood in the pulmonary capillaries only by the thin wall of 
the air vesicle and the thin capillary wall. Carbon dioxid, 
water, and other waste matters pass from the blood through 
this thin partition into the air vesicle, to be sent out by 
later expiration. Oxygen from the air in the vesicle passes 



104 PHYSIOLOGY. 

through these layers into the plasma, and most of it is 
quickly picked up by the colored corpuscles. The colored 
corpuscles are the carriers of oxygen. 

Hemoglobin and Oxyhemoglobin. — As has already 
been stated, the hemoglobin in the colored corpuscles has 
an affinity for oxygen. Hemoglobin is of a dark color, 
and gives the dark color to the blood which enters the 
lungs. When oxygen unites with the hemoglobin it forms 
oxyhemoglobin, which is of a bright red color. Hence 
the change in the color of the blood in the lungs from a 
dark bluish red to a bright scarlet. This bright blood is 
usually called " arterial," and the dark " venous " ; but it 
must be remembered that the blood in the pulmonary 
artery is dark, and in the pulmonary veins bright. 

Amount of Oxygen Used. — We take into the blood 
only about one fourth of the oxygen of the air that passes 
through the lungs. In like manner the blood, passing 
through the tissues, gives up to frhose tissues (in ordinary 
circumstances) only about half the oxygen it contains (per- 
haps holding the remainder as a reserve). 

The Gases in the Blood. — If a quart of blood be placed 
under the receiver, and the air exhausted, it will be found 
that the blood contained about three fifths of a quart of 
gas. This gas is a mixture of oxygen, carbon dioxid, and 
nitrogen, and the proportions vary according to the kind 
of blood taken. If from the left heart, or pulmonary veins, 
there will be more oxygen and less carbon dioxid ; if from 
the right heart, pulmonary artery, or caval veins, there 
will be less oxygen and more carbon dioxid. Oxyhemo- 
globin blood (" arterial blood ") contains about one fifth its 
volume of oxygen. Hemoglobin blood ("venous blood") 
contains about one tenth its volume of oxygen. Oxy- 



RESPIRATION. 



105 



hemoglobin blood holds about two fifths its bulk of carbon 
dioxid, while hemoglobin blood has nearly one half its 
bulk of carbon dioxid. 

THE GASES IN THE BLOOD. 
From 100 volumes of — May be obtained 



Oxyhemoglobin (arterial) blood 
Hemoglobin (venous) blood . 



Oxygen. Carbon dioxid. Nitrogen. 
20 vols. 40 vols. 1 to 2 vols. 

10 vols. 46 vols. 1 to 2 vols. 



Illustration of the Changes in the Color of the Blood. — The 

changes that take place in the color of the blood, both in the lungs 
and in the tissues of the other parts of the body, may be illustrated as 




The bo* 

Fig. 47. Changes in the Color of the Blood. 

follows : Prepare a heart as directed on page 45. Use for the liquid a 
strong solution of litmus, neutralized or slightly alkaline ; place in the 
throat of each funnel a small sponge. Saturate with ammonia the 
sponge in the funnel representing the capillaries of the body, and 



106 PHYSIOLOGY. 

saturate with hydrochloric acid the one in the funnel representing the 
capillaries of the lungs. 

Now, on working the heart the liquid will change from red to blue 
in the funnel representing the body, and from blue to red in the funnel 
representing the lungs. 

" Anatomically there are two lungs, and the heart lies between them ; 
physiologically, the lungs form a single organ, which is interposed be- 
tween the two hearts." — Wilder. 

The Changes in the Blood. — What does the blood do 
with the oxygen that it gets in the lungs, and where did it 
get the carbon dioxid and other impurities that it brings 
to the lungs ? Let us follow the blood and see. From 
the pulmonary veins the blood goes to the left heart, and 
is pumped to. all the tissues except the lungs. Let us 
follow a branch of the aorta that leads to a muscle. 

The Production of Heat and Motion in the Body. — 

When a muscle works it becomes warmer. This has been 
repeatedly proved by experiment. We know that we feel 
warmer when we exercise. We know that the blood is 
flowing more rapidly through the muscle when it is at 
work. This more rapid stream brings the muscle more 
oxygen. This it needs, for the heat of the muscle is pro- 
duced by the oxidation of substance in the muscle. We 
have seen that the oxidation of iron produces heat, and it 
is the oxidation of the materials in the candle that enable 
it to give out heat. But our bodies do not give out the 
intense heat of a burning candle, nor do they produce 
light, as is the case with the oxidation of iron and magne- 
sium when those metals are burned. The slow oxidation 
of the metals, in the presence of moisture, is more like 
the oxidations in our bodies. It is by the oxidations of 
the muscle (or substance in it) that the muscles produce 
heat and that form of energy which gives motion. In the 



RESPIRATION. IO? 

case of the rusting of the metals there is as much heat pro- 
duced as when they are burned, but the heat is so slowly 
generated that it is given off about as fast as it is pro- 
duced, and we do not notice it. The oxidation produces 
the waste matters, just as the burning of the various 
substances produces waste. 

Oxidation of Live Tissues and Dead Matter. — In our 

experiments with oxygen we see that substances which 
burn in air will burn still more actively in oxygen. But 
we must not infer from this that in our bodies the oxida- 
tion of the tissues would be faster in pure oxygen. This 
is not the case. The tissues take as much oxygen as they 
need (if they can get it), and they will not take any more 
than they need, no matter how much is offered them. It 
does not injure the body, nor any part of it, to breathe 
pure oxygen. It does not make one feverish, it does not 
produce any more heat, nor make one "live faster." This 
point should be specially noticed, as it was formerly sup- 
posed that the oxidation of the tissues of the body was 
just like any combustion of dead material. But the tissues 
are alive. They know their own needs. Each cell takes 
what it requires and no more, just as it does of food 
brought to it by the blood. The amount of oxygen pres- 
ent does not determine the degree of muscular activity, 
but the degree of muscular activity determines the amount 
of oxygen consumed. 

Increased Blood Flow is the Result of Exercise. — 

When we exercise, the muscles need more oxygen. They 
also need to have removed the waste matters that they are 
so rapidly producing at this time. How is the oxygen 
brought and the waste removed ? By the blood, you 
answer. True ; but what makes the blood come and 



108 PHYSIOLOGY. 

go faster at this time ? By reflex action, you reply. The 
muscles send a message to a nerve center, and this nerve 
center sends back a message to the blood tubes, making 
them widen, and the heart also may be made to beat 
faster. But would it do any good to have the blood flow 
through the muscles faster, if it could not bring more oxy- 
gen, and take away and get rid of more wastes ? You 
will say no. To give the extra oxygen, and take out the 
carbon dioxid, the lungs cannot, of themselves, take in and 
send out air. The work of pumping air depends on the 
muscles of respiration, the diaphragm, and the muscles 
that elevate the ribs. These will not work faster unless 
they are ordered to do so. A message must be sent to 
these telling of the need in the muscles that we are con- 
sidering, say one of the large muscles of the lower limbs. 
Thus, by a series of reflex actions, all these processes are 
kept in harmonious relation to each other. It must be 
borne in mind that increased blood flow is the conse- 
quence, and not the cause, of the increased activity of the 
tissues. 

Temperature of the Body. — Insert the bulb of a thermometer into 
the mouth, and keep it there three or four minutes to find the tempera- 
ture of the inside of the body. For this it is better to use a clinical 
thermometer, if one can be obtained. The average temperature of the 
tissues within the body is about 98. 5 F. 

How the Body is like a Stove. — The body may be 
compared to a stove. Into one we put fuel and produce 
heat. In the other we get heat from food. 

How the Body differs from a Stove. — But the body is 
not like the stove in burning the fuel (food) directly. The 
food is first made into tissues, or " storage compounds " in 
the tissues. It is as though we were to build a stove 



respiration: 109 

entirely of coal, and then start a fire in it. In that case it 
would produce heat not merely by burning in one place 
within, but would be burning throughout the whole of its 
substance. This is the case with the body. 

Oxidation in Tissue the Source of Heat in the Body. — 

We have seen that the muscles constitute nearly half of 
the weight of the body. We know, too, that they are more 
active than most of the tissues. We would now naturally 
infer, as indeed is the fact, that they are the chief source 
of the heat produced in our bodies. 

The tissues of the body are oxidizing all the time. But 
when they are in vigorous action they oxidize very much 
more rapidly. 

Next to the muscles, in importance as a heat producer, 
is the liver, which is the largest gland in the body, and, as 
we shall soon see, one of the most active. The blood, as 
it leaves the liver by the hepatic vein, is hotter than 
anywhere else in the body. 

How the Body is like a Locomotive. — But it will be 
better to compare the body to a locomotive, as we produce 
not only heat, but motion as well. 

If a visitor from another planet, unfamiliar with such 
creatures as we are, were to observe closely a man and a 
locomotive, he would see several points in common : — 

1. Both are warm. 

2. Both move. 

3. Both use fuel (food or coal). 

4. Both take in air, and (if it were a winter day) 

5. Both give off " steam " (which is essentially the same 
in the two, carbon dioxid and water vapor being the chief 
constituents). 



IIO PHYSIOLOGY. 

How the Body differs from a Locomotive. — By a 

closer examination he would find out some of the differ- 
ences that we have noticed : — 

1. That the body does not get hot enough to burn; i.e. 
the oxidation is relatively slow, and is not combustion. 

2. That the oxidation of the body never produces light. 

3. That the oxidation here is always in the presence of 
moisture. 

The Amount of Carbon Dioxid given off. — When the 
breath is held for some time, the carbon dioxid in the ex- 
pired air may reach 7 or 8 per cent. During violent 
exercise the amount of carbon dioxid given off may be 
from two to two and a half times as much as when we are 
at rest. The amount of carbon dioxid given off is in- 
creased in cold weather, and by taking food, and decreased 
from one fifth to one fourth during sleep. Oxygen is 
carried chiefly in the corpuscles, but the carbon dioxid is 
carried in both plasma and corpuscles. 

Storage of Oxygen in the Tissues. — The activity of the tissues 
from their oxidation does not necessarily mean that the oxidation is 
direct ; that is, that the oxygen is used as soon as it is brought to the 
tissue. For instance, in the muscles it is believed that the oxygen is 
stored in some form, probably in combination, so that it can be used 
when needed, perhaps much more rapidly than could be supplied by the 
respiration at the time. If we study the chemistry of explosion, we 
learn that it is a very rapid combustion. In the explosives are ma- 
terials that unite instantaneously, instead of slowly burning, as in the 
case of ordinary combustibles. 

The Action of Muscles like an Explosion. — Now, many physiolo- 
gists hold that a sort of explosive compound is formed in the muscles, 
and that when the muscle acts it does so as the result of the explosion, 
so to speak, of this material. And, to carry out the figure, the nerve is 
compared to the match that ignites the explosive. A little heat is 
enough to cause the most violent explosion. So the force that passes 



RESPIRA TION. 1 1 1 

along a nerve fiber is slight. But it rouses a great amount of energy 
that lay dormant in the muscle. It would seem to have "touched off" 
a lot of explosive material that was already there, rather than merely 
started an action that depends on the comparatively slow process of 
respiration at the time. We cannot follow this theory farther, as it 
takes us too deep into the study of chemistry in its most difficult 
branch, — physiological chemistry. 

Summary of Respiration. — The tissues need oxygen ; 
air is pumped into the lungs ; this air gives oxygen to the 
blood ; the blood carries it to the tissues. 

In oxidizing, the tissues produce energy (heat and mo- 
tion) and give off waste matter (water, carbon dioxid, etc.); 
these the blood carries to the lungs, the lungs give them 
to the air, and the air carries them out of the body. 

The pumping of the air in and out may be called " me- 
chanical respiration." The changes between the air and 
the blood in the lungs we will call the " ventilation of the 
blood," and the interaction of the blood and the tissues 
the "real, or internal respiration." 

The Two Breaths. — " Every time you breathe you 
breathe two different breaths ; you take in one, you give 
out another. The composition of these two breaths is 
different. Their effects are different. The breath which 
has been breathed out must not be breathed in again." — 

KlNGSLEY. 

Breathing Expired Air. — The air in the vesicles re- 
ceives from the blood carbon dioxid, water vapor, and 
other impurities above mentioned. It has been believed 
for a number of years that the organic impurities consti- 
tute the most dangerous element in expired air. Carbon 
dioxid, though to some extent a poison, is not very injuri- 
ous in such quantities as ordinarily exist in the air, even in 
poorly ventilated rooms ; while the headache and drowsi- 



112 PHYSIOLOGY. 

ness that one experiences in a close room where there are 
a number of people is due to the reabsorption of these 
organic matters. It is not due to lack of oxygen, for the 
oxygen may be reduced to 13 per cent without causing 
discomfort. A person may breathe air containing 1 per 
cent of carbon dioxid, with a corresponding reduction of 
oxygen, when the carbon dioxid is generated by ordinary 
chemical processes (as in a small room with a large kero- 
sene lamp, or a gasoline stove); but air having 1 per 
cent of carbon dioxid produced by breathing is highly 
injurious, because it contains the organic impurities above 
noted, and the term "crowd poison" has been employed 
for this material. Later investigators, however, maintain 
that there is nothing injurious in the freshly expired breath. 

Alcohol and Consumption. — At one time it was widely 
believed that alcohol was a cure for consumption. This is 
now known to be so far from the real facts of the case 
that it is well established that certain forms of consump- 
tion are directly attributable to the use of alcoholic drinks. 
Under the former mistaken view many consumptives used 
alcoholic liquors to their own injury. But time and ex- 
perience have taught that they only exaggerate the trouble. 



Summary. — 1 . In the lungs the air and blood are brought very 
close together, only the wall of the capillary and that of the air vesicle 
intervening. 

2. Through these two layers oxygen passes from the air vesicle 
into the blood. Carbon dioxid, water vapor, and other wastes pass 
from the blood into the air vesicle. 

3. The mucous membrane of the air passages secretes mucus which 
is driven toward the nostrils by the cilia. 

4. The chest is lengthened by the depression of the diaphragm, and 
widened by the elevation of the ribs, giving greater space, which is 
filled by external air expanding the lungs. 



RES PI R A T/OAT. 1 1 3 

5. Inspiration acts in opposition to resistances, whose elastic re- 
action performs ordinary expiration without active effort 

6. There are four heart beats for each respiration. 

7. The lungs are never emptied. 

8. Respiratory capacity may be increased by exercise and practice. 

9. Respiration is controlled by the nervous system ; the respiratory 
center is in the spinal bulb. 

10. Internal respiration is an oxidation in the tissues, illustrated by 
the rusting of moist iron. 

11. In passing through the lungs air loses oxygen, and gains water, 
carbon dioxid, and other wastes. 

12. Oxygen is carried chiefly by the colored corpuscles of the blood ; 
it unites with hemoglobin in the corpuscles, forming oxyhemoglobin, 
and gives the blood its bright scarlet color. 

13. The energy of heat and motion in the body results from the 
oxidations in the tissues. 

14. Air once breathed is unwholesome. The air of living and sleep- 
ing rooms needs constant renewal. 

Questions. — 1. Is it a good thing to see how long one can hold his 
breath ? 

2. Should the head be covered by bedclothes? 

3. What are the "lights " in an animal? 

4. How is respiration affected by a stooping posture? 

5. In what part of the lungs is the best air? Where the worst? 

6. Can you explain how respiration affects circulation? 

7. Is it easy to determine by the color of blood flowing from a 
wound whether it is arterial or venous? Why? 

8. Of what advantage is it that the cartilages of the windpipe are 
C-shaped and not complete rings? 

9. How is it that in respiration 5 per cent of the oxygen disappears 
while only 4 per cent of carbon dioxid appears in its place in the 
expired breath ? (Seep. 102.) 



CHAPTER VII. 

VENTILATION AND HEATING — DUST AND BACTERIA. 

Need of Proper Ventilation. — When one is actively 
exercising his muscles he may keep warm outdoors through 
our winter days. For the heat of the body depends on its 
internal fires, the oxidation of its tissues. But if we are 
inactive, these fires burn feebly, and we need outside heat. 
While air is free, it really costs a good deal of mon^y to 
have it properly warmed. 

A Lack of Effective Systems of Ventilation. — Lung 

diseases are rare in the regions where the windows and 
doors may be kept open most of the days of the year. It 
is from shutting ourselves in so closely that we suffer. 
This is especially true where many people are housed in a 
comparatively small space, as in many public buildings. 
But in our private dwellings, even when the owners are 
amply able to secure the most sanatory appliances, defec- 
tive apparatus is often put in. Any system that does not 
provide for a constant renewal of the air is defective. 

Grates as Heaters and Ventilators. — Grates will aid 
largely in renewing the air. Although in themselves they 
merely have provision for sending radiant heat out into the 
room and much air up the chimney, yet, without any 
special provision for inlet of air to the room, they draw air 
in through every crack and crevice. It would probably be 
very much better to have special ducts for the admission 

114 



VENTILATfON AND HEATING. 115 

of air, which is suitably warmed while on its way into the 
room, and to make the doors shut snugly, and to have 
double windows, as then both the admission of fresh air 
and the regulation of heat will be better secured. But 
it is a serious question whether, with all our modern ap- 
pliances, conveniences, and luxuries, we have better air 
in our houses, and take cold less frequently, than our 
ancestors who depended more on the fireplace, even if 
they did " roast on one side while they froze on the other." 
Fireplaces are expensive as mere heaters, but they are 
excellent ventilators. 

Ventilating Flues around a Smoke Flue. — If small 
ventilating flues could be built around the flue of the main 
heating apparatus, and connected with the various rooms 
of the house, air could be drawn from these rooms by 
ascending currents created by the heat of the central smoke 
flue. Such flues surrounding smoke flues, would have the 
added advantage of protecting the house from fire through 
the too common " defective flue." 

The General Principles of Ventilation. — Of the forces 
that operate to renew the air two are natural, diffusion 
and the wind ; and two are artificial, warm air shafts and 
fan systems. 

Diffusion. — Gases tend to mix. We know that if a 
bottle containing an odorous substance be opened in 
a room where there are no air currents the odor tends to 
spread equally through the room. So if a person is in 
one corner of a large room, where there are no inlets 
or outlets, and no currents, as he uses the oxygen immedi- 
ately around him, the oxygen farther away will diffuse 
toward him so that he will continue to get oxygen till the 
amount of oxygen in the room is nearly exhausted. So, 



Il6 PHYSIOLO&Y. 

too, the gases that he breathes out will not remain confined 
to the space directly about him, but will spread nearly 
evenly throughout the room. The same takes place in the 
open air, without wind. So, then, if the windows and 
doors are open, the air of the room will, by diffusion, be 
renewed. 

Wind. — Motion of the air renews faster than mere dif- 
fusion. Strong wind forces its way through the cracks 
around windows, and when windows are open on opposite 
sides of a room there is usually enough breeze to renew the 
air. But during the greater part of the year this cannot be 
done. 

Artificial Renewal of the Air. — The renewal of the 
air in most cases depends on the fact that heated air rises. 
Heat expands air. It is then lighter, bulk for bulk, than 
cooler air. The heavier surrounding air presses the lighter 
air upward. If there are outlets above and below, the 
heavier, colder air will press in at any opening left below, 
and push the lighter, warmer air out above. 

The Common Stove. — In the case of the common stove 
we very well know that there are currents of heated air 
rising above the stove. Children make whirligigs and 
various toys to place in these up-currents above stoves. 
Air is, at the same time, flowing toward the stove along 
the floor and lower part of the room. Cold air can usually 
be detected entering around the windows and doors, which 
presses downward and toward the source of heat. The 
stove does not do much to renew the air in the room 
except in this general way ; some heated air escapes at 
openings in the upper part of the room, and some is passed 
out through the stove, taken in as a draft. But in the 



VENTILATION AND HEATING. \\J 

main, the action of the heat of the stove is to make a 
current of warm air up from the stove, which current 
passes along the ceiling to the more distant corners of the 
room, then descends, joining the cold air, and repeating 
the round. 

A Stove and Jacket. — In some cases a jacket is placed 
around a stove, and a duct from the outer air connects 
with the lower part of the space inside of the jacket and 
outside of the stove. Then as the air heated by the stove 
rises, fresh air is drawn in from outside to be warmed. 
In this case the direct heat from the stove is shut off from 
the room. Heat radiates in straight lines. When one 
holds out his hands beside a stove the heat he receives is 
radiant heat. Most of the heat from a grate is radiant 
heat. But in a jacketed stove the heating by air currents 
is called heating by convection. 

The Furnace. — Now a furnace is practically a jacketed 
stove (almost always placed in a basement). Furnaces 
have this good feature that they are all the time sending 
fresh air into a room. 

Foul-air Shafts and Fans. — Although in private dwell- 
ings heated by furnaces there is no special provision for 
the escape of foul air, there is ordinarily sufficient renewal 
of the air. But in public buildings there should be escape 
flues for foul air. 

Frequently a large foul-air shaft is built in some central 
part of the building, and a small stove placed in it to create 
a sufficient up-current. In many public buildings the cur- 
rents created by heat are insufficient to renew the air 
properly. Fans are used, which force the air, properly 
heated, into the room. 



Il8 PHYSIOLOGY. 

Direct Heating. — In heating by steam or hot water, ii 
the radiators are placed in the room they give direct or 
radiant heat. This system is called direct heating. In 
itself it has no provision for renewing the air. It gives 
direct heat, and produces air currents within the room ; 
and any change in the air is wholly incidental, from escape 
of heated air in the upper parts of the room and corre- 
sponding suction of outside air through such openings as 
the carpenters have left below. 

Indirect Heating. — In indirect heating, coils of steam 
or hot-water pipes are placed in air shafts which lead up 
to the rooms above, and also have ducts to the outside. 
As the air is heated by the heat of the pipes it rises into 
the rooms above, and fresh, cold air presses in through the 
ducts, to be, in turn, heated and sent up. If there is at 
the same time a proper escape for the foul air, this makes 
an excellent system. 

A Combination of Direct and Indirect Heating. — In 

many situations the direct and indirect may be advan- 
tageously combined. Where there is a grate in a room, it 
serves very well as a foul-air shaft, especially when there 
is a fire in the grate. It is well to have the flue from the 
grate in the same chimney with that from the smoke pipe, 
as then the heat from the smoke will cause a constant up- 
draft in the grate flue, whether there is a fire going in the 
grate or not. 

With a grate, in private houses, there is ordinarily no 
need of other foul-air shaft for any room. But it is very 
desirable to have at least some " indirect" heat, so that 
the fresh air introduced will be sufficiently heated. 

If the introduction of air is thus provided for, it is then 
safe to put on double windows and make the cracks around 



DUST AND BACTERIA. 119 

the door very tight. Without any special provision for the 
renewal of the air these cracks are the means of safety. 

In houses heated by furnaces, steam, or hot water, the 
floor is likely to be warmer from the escape of heat from 
the heater itself, and from pipes or air ducts under the 
floor. 

Double Windows. — There is a very common misunder- 
standing as to the cold felt near a window in cold weather. 
It seems that air is entering ; but a little reflection will 
show that even if the window were air-tight this effect 
would be produced, for the air near the window is cooled 
by losing heat to the outer air. The air next to the win- 
dow, thus cooled, is heavier, and falls to the floor ; and if 
there is any source of heat in the room, this cold air will 
pass along the floor to that source of heat, up from the 
heating body to the ceiling, and across the ceiling, and so 
on around again. There may thus be currents without 
any appreciable change in the quality of the air. It is 
economy to use double windows and prevent the loss of 
heat through the glass. So both economy and comfort 
suggest to us that we reduce as much as possible cracks 
around doors and windows, use double windows, make ves- 
tibules at entrances, and build special ducts by which fresh 
air may enter, and heat it properly on its way in. 

DEAD DUST. 

The Air is washed by Rain or Snow. — Every one 
will recall how delightfully refreshing the air is after a rain 
or a snowstorm. This is not due merely to the fact that 
the air is cool. It is clean because it has been washed. 
The rain and snow absorb a considerable amount of the 
various impure gases that are in the air. But raindrops 



120 PHYSIOLOGY. 

and snowflakes bring down with them many particles of 
dust that were floating in the air. Take some of the snow 
that has fallen in a town. It looks pure in its almost 
dazzling whiteness. But melt some of it, and you will 
usually find a decided tinge darkening the water, showing 
that as the flakes sifted down through the air they caught 
myriads of particles of dust. 

The Sources of Dust. — Where soft coal is used to any 
large extent it is one abundant source of this dust. In 
summer dust has many sources. The dust that blows into 
your face, and perhaps into your mouth, may be made of 
dry soil. Take a dry clod and drop it ; it falls quickly to 
the ground. Pulverize it in your hand before dropping it, 
and considerable of it floats in the air for some time. Any 
substance that is easily dried and pulverized may form 
part of the common dust. The dust that you wipe from 
your eye, or is caught by the mucus of the nasal passages, 
may, instead of being made of clean soil, be from the 
excreta of horses, decayed leaves, wood, grass, etc. In- 
doors we are constantly making dust by wearing out our 
clothes. Many of the tiny particles that we see floating in 
the sunbeams are bits of cotton or woolen fibers. Shake 
any garment in a beam of light to see how much, and how 
easily, dust is given off*. The worn-off particles of our 
shoes, books, floors, all contribute to the ever-present 
dust. 

The Effect of Dust on the Lungs. — Now, this dust (so 
far as it is mere dead, dry matter, not considering it as a 
poison) is irritating to the lungs and respiratory passages. 
There is provision, as we have seen, for catching and 
getting rid of a good deal of it. 

But still much is taken into the lungs. Examination 



DUST AND BACTERIA. 121 

shows that the lungs have many black specks from parti- 
cles of carbon, etc., that have become lodged, and are of 
no benefit, to say the least. 

LIVE DUST. 

Composition of Live Dust. — Bad as this dead dust is, 
the injury from.it is slight compared to that from live dust. 
We know that certain seeds float in the air, carried along 
by the wind. But these aie comparatively heavy, and soon 
sink to the ground. 

We all know pollen. At certain seasons it forms, in the 
vicinity of cornfields, for instance, a considerable part of 
the dust. This is alive. It will grow if it falls on the 
right kind of a surface, the stigma of the right plant at the 
right time. Such dust will not grow in our bodies. We 
do not furnish a soil in which it can grow. It merely adds 
to the amount of irritating dust. 

Puffballs and Molds. — We have seen puff balls give 
off a cloud of dust when they are crushed. This dust is 
composed of live spores that will grow in suitable places 
and conditions. So, too, from a patch of mold, when 
brushed, we often see a little cloud of dust. These are a 
few instances of kinds of living dust that simply act on us 
like so much dead matter. 

Yeast. — If we set a tumbler of cider on a table in a 
warm room, in a few days it ferments. This is due to 
yeast that has gotten into it. Boil the cider to kill any 
yeast that is already in it, and cork it securely so that air 
cannot get at it, and it will not ferment. Dried yeast 
germs float in the air, settle on the fruit or in the cider, 
and cause it to ferment, Cider is a good soil for yeast. 



122 PHYSIOLOGY. 

Disease Germs. — But there are floating in the air many 
kinds of spores that may grow in our bodies. We know 
that many of our contagious diseases are due to the growth 
in our bodies of some of these spores. Our bodies are a 
good soil for certain germs. The germs that cause con- 
sumption, typhoid fever, Asiatic cholera, erysipelas, diph- 
theria, and some forms of blood poisoning are well known. 
Microscopists know them when they see them as readily 
as we know peas from beans. And it is proved beyond 
all doubt that these germs get into our bodies by being 
breathed in, or by being eaten in food, or in drinking 
water, or by introduction into the blood in wounds. We 
have reason to believe that smallpox, yellow fever, measles, 
and scarlatina are caused by germs, but these diseases have 
not been studied so successfully. 

How to avoid Germs. — How can we avoid or get rid 
of dusts of these kinds ? To exterminate any plant, we 
try to keep the seeds from ripening, and to kill all that do 
ripen. Let us take a case that, while not pleasant to con- 
template, is too terribly true to allow of being called an 
imagined case. 

The Danger from Consumption. — A consumptive ex- 
pectorates on the pavement. In this sputum are probably 
hundreds, if not thousands, of germs known as bacilli 
{Bacillus tuberculosis). They are alive. Now, so long as 
they remain on the pavement they do no harm. The 
sputum dries. But the bacilli are not killed by drying. 
With other dry material from the pavement they form 
part of the common dust. Any one of us may breathe 
some of this kind of matter any day, for there are persons 
afflicted with this dreaded disease in every community. 
Our bodies furnish the very best soil for the germs. 



DUST AND BACTERIA 



123 



How to avoid the Danger. — Now, of course, all such 
material known to be highly dangerous ought to be de- 
stroyed. If those suffering from such diseases were care- 
ful to burn all such matter, most of the seeds of this disease 
would be killed. Thus in time we might stamp out the 
disease, as a scourge of Canada thistles. But so long as 
people expectorate upon the floors and pavements it will 
be difficult to prevent the spread of such germ diseases. 




YH 



■/ 



Bacillus of Tuberculosis (x 1000) 




Bacillus of Typhoid Fever (x 1200) 



Typhoid Bacillus, showing flagella 



*L' W 



ft» 






f -J « 







Bacillus (Spirillum) of Asiatic Cholera Bacillus of Hog Cholera ix 1000) 

Fig. 48. Types of Bacilli, showing Morphologic Characters and Arrangement. 

In hospitals such matters are now looked after with the 
greatest care, and in private houses where there is intelli- 
gence on these subjects. And it is encouraging to note 
the awakening of the public to the significance of the teach- 
ings of modern science on this subject, as shown by the 
fact that many of the railroad and street car companies 
now prohibit spitting on the floors of cars, not merely be- 
cause it is uncleanly, but on the express ground that it is a 
means of spreading infectious diseases. 



124 PHYSIOLOGY. 

Outdoor Treatment of Consumption. — Lung diseases 
usually accompany close confinement, but are rare with 
those who live in the open air. Formerly many consump- 
tives were sent to Florida, Colorado, the Adirondacks, and 
the mountains of North Carolina. Whatever advantages 
there may be in mild climate, dry air, sunshine, etc., there 
is little doubt that the chief benefit came from the fact 
that the patient spent much of his time in the open air, 
and, when indoors, had the windows open day and night. 

It is not now considered necessary to send a consumptive far from 
home. The main thing is to send him out of doors. He may sleep on 
a porch, secluded and protected by canvas curtains. In Massachusetts, 
Pennsylvania, and Illinois there are colonies of consumptives living in 
tents or cabins. Often the cabins are entirely open on one side. When 
necessary they are warmed by stoves. Suitably clothed, the patient 
may be comfortable in any season or weather. In this outdoor treat- 
ment little medicine is used, but great care is taken to supply ample and 
suitable food. This method has cured a large per cent of the patients. 
Of all the remedies for lung trouble, the best, the cheapest, and the 
most common, is fresh air. Yet many persons dread " exposure," but 
the more closely they remain housed, the more sensitive they become 
to cold and rough weather. It is a rare thing to " take cold " in camp. 
The increased vigor with which one returns from a camping trip is 
partly due to breathing fresh air twenty-four hours a day. 

Bacteria. — These disease germs are the smallest and 
simplest of living things. They are plants ; and while all 
of them that are well known have their scientific names, 
just as the larger plants have, they are all included in one 
general group designated as bacteria. 

How to avoid Dust. — We need to learn a good deal 
more about avoiding and destroying dust, and the things 
that make dust. 

Towns and cities need more sprinkling to keep the dust 
down. Much more of the refuse and street sweepings and 



DUST AND BACTERIA. 1 25 

cleanings ought to be burned. The dust of a house should 
always be burned, as we know not what germs of disease 
may be in it. If we burn it, we shall surely not have to 
sweep up that dust again. If we send it out of doors it 
may come back, and we may have to handle it again and 
again. 

Sweeping and Dusting. — So far as possible let us avoid 
things that make dust. When we sweep a carpet, a con- 
siderable share of the dust comes from the carpet itself, 
especially if the carpet is old. Curtains and tapestries of 
nearly all sorts not only hold dust, but contribute a good 
deal to it. Those who write on such subjects recommend 
hard wood floors with rugs instead of carpets. The rugs 
can be taken out of doors and shaken, and the floors wiped 
with a moist cloth, so that little dust is left floating in the 
air of the room. Compare this with the condition that 
holds after the ordinary sweeping of a carpeted room with 
the common broom. The dust fills the air, only to settle 
back on the floor and furniture. Then comes the whisk 
broom, the so-called dusting. Well, it is dusting ! It fills 
the air once more with dust. But do we get rid of it? 
Wiping off the dust with a moist cloth takes most of it 
away on the cloth. For those who cannot have hard wood 
floors a most excellent substitute (and in some respects 
better) is oilcloth or linoleum. 

Sweeping the Sick Room. — The improved carpet 
sweepers are not only convenient, but sanatory. Many a 
well-meaning person will sweep a carpet in a sick room 
with an ordinary broom when the patient is suffering from 
lung disease, thoughtless of the fact that a little dust in 
sight, and perhaps on the shoes, is of much less signifi- 
cance than dust in the air we breathe. No one likes dust 



126 PHYSIOLOGY. 

on the floor, but better a thousand times there than in our 
lungs. 

Lung Diseases. — Statistics seem to show that one 
seventh of the deaths among the civilized races is due to 
lung diseases. The best authorities are now agreed that 
consumption is not hereditary. But it appears that there 
may be inherited a tendency to this disease, so that, if ex- 
posed, such persons are more likely to contract the disease 
than those not so predisposed. 

Probably anything that lowers the general vitality makes 
the system more ready to succumb to any of these con- 
tagious diseases. We have all noticed what a difference 
there is among individuals in the readiness with which they 
" catch" contagious diseases. 

Destruction of Germs by Colorless Corpuscles. — It is 

believed by some physiologists that the colorless blood 
corpuscles may take these germs of disease into their sub- 
stance, and destroy or change them so that the disease is 
warded off. In other words, they may be compared to a 
cat that catches and eats the mice which invade a house. 

How to ward off Contagious Diseases. — A good gen- 
eral condition of the body helps greatly to ward off dis- 
eases of this nature. A cheerful condition of mind and 
body should be cultivated. In times of widespread con- 
tagious disease, if one is terrified into the belief that he is 
going to have the disease, he is more likely to take it. 

Thorough cleanliness, plenty of direct sunshine, care in 
diet, and the keeping of the body in good tone, all these 
reduce the chances of " taking " contagious diseases. 

An open-air life, abundant nutritious food, and freedom 
from anxiety are probably the best restoratives for incipient 
consumption. 



DUST AND BACTERIA. \2J 

The Bacteria of Putrefaction. — Besides the disease- 
producing bacteria, there are others that cause decay and 
putrefaction of various kinds. They cause our richer foods 
to "spoil," milk to turn sour, butter to become rancid, etc. 

While these bacteria do not cause disease in the human 
body, they often make food poisonous. The cases fre- 
quently reported of poisoning from eating ice cream, 
cheese, sausage, etc., are in many cases due to bacteria in 
them. We should, in the first place, be careful to get 
good, fresh material. In the second place, it should be so 
kept as to prevent the introduction and development of 
bacteria in it. Bacteria need heat for their growth (as we 
so well know is the case with the higher plants). They 
also need moisture. 

The Preservation of Foods. — So our principal modes 
of keeping foods from spoiling are to keep them in a cold 
place, or to dry them. Or we heat them, and shut them 
away from the air, as in our various modes of canning and 
preserving foods. Salting and smoking meats, etc., preserve 
them by preventing the growth of bacteria. Cold does 
not usually kill bacteria. So milk that has been kept in a 
refrigerator, and that seems sweet, may have in it a stock 
of bacteria, and after we drink the milk the heat of our 
bodies favors their development. There are now known 
ways of killing the bacteria in milk and other liquids, known 
as " sterilizing," that make us safe from this danger. 

Although the main subject of this chapter is air and 
ventilation, it has been thought best to touch briefly the 
subject of bacteria in food t as the bacteria are so widely 
disseminated by the air. One of the earlier and still in- 
teresting works on this subject is Tyndall's Floating Matter 
of the Air. 



128 PHYSIOLOGY. 

But let us now turn from the air and respiration to 
another, yet closely allied subject. 

The Need of the Removal of Waste. — When we 
awaken on a cold winter morning we are likely to find that 
the fire in our hard coal stove has burned low. Not enough 
heat is given out. What is the trouble ? Is it merely that 
more coal is needed ? We put another hod of coal in the 
magazine (though some usually remains). Does this bring 
the desired result ? No. We open the draft Is this suffi- 
cient ? It is not» We must shake down the grate and 
clean out the clinkers. The removal of waste is often 
more necessary than the addition of a fresh supply of ma- 
terial. It is often a more serious matter to have the waste 
pipe leading to the sewer clogged than to have the water 
supply cut off. It is often more to be desired that the 
garbage cart take away decaying matter than that the 
bread wagon arrive. The demands of nature for the ex- 
pulsion of excreta are imperative, while we can withstand 
the cravings of hunger for a while. So we shall turn our 
attention for the present to the immediate demand for the 
removal of wastes, and later consider the equally impor- 
tant, but less importunate, question of supply and renewal 

Reading. — (i) Bacteria, (2) Dust and Its Dangers, 
(3) Drinking Water and Ice Supplies, Prudden ; Ventila- 
tion and Warming of School Buildings, Morrison ; Sanitary 
Conditions of Schoolhouses, Lincoln (American Public 
Health Association); Disinfection, Sternberg (American 
Public Health Association) ; Micro-Organisms and Disease \ 
Klein ; The Wilderness Cure, Marc Cook. 



Summary. — 1 . Lung diseases usually accompany close confine- 
ment, but are rare with those living in the open air. 



DUST AND BACTERIA. 1 29 

2. Air in rooms needs constant renewal. 

3. Grates are good ventilators, but not economical heaters. Grates 
heat very unevenly. 

4. Stoves are economical heaters, but poor ventilators. Stove heat 
is also very uneven. 

5. All crowded, rooms, as schoolrooms and churches, need special 
inlets for fresh air and outlets for foul air. 

6. The most common means of withdrawing the air is by foul-air 
shafts. Heat is the force relied on, but the removal of foul air is usually 
inadequate, on account of the slowness of the current or the narrowness 
of the outlet, or both combined. 

7. Fans are much more certain to be effectual. 

8. Steam and hot water may heat directly (by radiation) or indi- 
rectly (placed in flues). A combination of direct and indirect heating 
favors economy and efficiency. 

9. Dust as mere dry dead matter is irritating. 

10. Disease germs may form part of the dust of the air. 

11. Most of our contagious diseases are known to be due to bacteria. 

12. Burning is the surest method of destroying germs. 

13. Carpets, tapestries, and cloth-upholstered furniture add largely 
to the dust in houses. 

14. Putrefaction is caused by bacteria. 

15. Preservation of food depends on destroying, or excluding, or 
retarding the growth of the bacteria of putrefaction. 

Questions. — 1 . How can we renew the air of a room without having 
unpleasant drafts? 

2. Should bedroom windows be open at night? Is night air bad? 

3. What dangers in the use of hard coal? 

4. Should there be a damper in the smoke pipe of a hard coal 
stove? 

5. What do miners mean by " choke damp "? 

6. What is hay fever? Asthma? Bronchitis? Pneumonia? 

7. Compare stove and furnace heating. 

8. Compare heating by steam and by hot water. 

9. Is the air in the mountains or on the seashore better than else- 
where ? 

10. What regions are recommended for consumptives ? Why? 



CHAPTER VIII. 



EXCRETION. 

THE SKIN AND ITS FUNCTIONS. 

The Skin throws off Perspiration. — The energies of 
the body — heat and motion — are produced by the oxida- 
tion in its tissues. 
During this process 
waste products are 
formed, which if 
retained in the 
body would cause 
very injurious 
effects. 

How does the 
body get rid of 
these substances ? 
We have learned 
that the lungs 
throw off carbon 
dioxid, water, and 
certain putrescible 
organic matter. 
The skin is constantly throwing off wastes, collectively 
called sweat, or perspiration. 

The Structure of the Skin. — The skin has two layers, 
the inner, or dermis, and the outer, or epidermis. A 
bruise often loosens or breaks off a piece of the epidermis, 

130 




Fig. 49. Vertical Section of the Skin. 



EXCRETION 



131 



but seldom removes the dermis. The epidermis is thick 
over the palms of the hands and soles of the feet ; else- 
where it is thin. Not often seeing the whole thickness of 
the skin, we do not easily obtain an idea of its real thick- 
ness. The skin constitutes about one-fifteenth of the 
body's weight, and if tanned makes a moderately firm and 
thick leather very much resembling the pigskin used for 
covering footballs, striking bags, etc. 

Mouth of Sweat Duct 



Horny Epider 
mis 



Soft Layer 




Papilla 



Dermis 



Vein Artery 
Fig. 50. Section of Epidermis, showing Papilla. (Highly magnified.) 



The Epidermis. — The epidermis consists of many 
layers of cells packed closely together. The deepest cells 
may be compared to grapes with their cell walls plumply 



132 PHYSIOLOGY. 

filled out by the liquids of the cell. Suppose, for the 
inner layer, grapes set on end, and so closely packed 
together as to press each other into elongated prisms. 
Then layers less closely pressed, more nearly spherical; 
then layers of cells with less liquid in them, and somewhat 
shrunken, like raisins; then still dryer cells, flattened 
parallel with the surface of the skin ; and last, in the outer 
part, layers of cell walls, dry and empty, pressed flat like 
empty grapeskins. The flat cell walls come off in flakes 
(called dandruff from the scalp) from all the surface of 
the skin, and new cells are continually formed in the 
deeper layers. 

The Color of the Skin. — The pigment, which gives 
color to the skin, lies in the deeper layers of the epidermis. 
In albinos this is wanting ; in persons with a fair skin it 
is small in amount, in dark skins more abundant. Where 
the pigment is irregularly scattered it causes freckles, etc. 

A Blister. — A blister is caused by separating the outer, 
harder layer of the epidermis from the inner, softer, darker 
layer of the epidermis, as shown at B in Fig. 49. Serum, 
or Wood, fills the space between the separated layers. 

The Dermis. — The dermis consists chiefly of tough 
interlacing fibers. Hence the strength and durability of 
leather, which is the dermis preserved and prepared. The 
epidermis is usually removed in tanning. The dermis is 
richly supplied with blood capillaries and lymph capillaries, 
but the epidermis has neither. 

Papillae. — The outer surface of the dermis has numer- 
ous conical elevations. Over most of the skin there is no 
evidence of these papillae, as the epidermis envelops them. 
But on the palm and sole the papillae are in rows, and 
these rows are indicated by the fine ridges. 



EXCRETION. 



133 



Hairs and Fails. — Hairs and nails are outgrowths of 
the epidermis. Their deeper parts are embedded in the 
dermis, through which, from the blood, they derive their 
nourishment. Like the epidermis, they are dead in the 
outermost part, and are supplied by growth from beneath. 

Examination of the Skin with a Lens. — Place a linen tester, or 
good pocket lens, on the palm of the hand, and note the openings of 
the ducts of the sweat glands, or sweat pores. Count the pores within 
the square shown. Measure this square, and then estimate the number 
of sweat glands to a square inch of the palm. 

Epithelium or Epidermis 



Blood ,-•"' -~W 
Tube 





Compound Glands 
Fig. 51. Evolution of Glands. (After Landois and Stirling.) 

The Sweat Glands. — The sweat glands are minute 
tubes whose inner ends are closed, and whose outer ends 
open upon the surface of the skin. The tube going 
inward pursues a corkscrew-like course through the epi- 
dermis, then becomes straighter, and, having passed 



134 PHYSIOLOGY. 

through the dermis, is coiled up in a ball in the connective 
tissue lying just underneath the inner skin. The cells 
forming the walls of the coiled part differ from those of 
the duct, or straighter part of the tube. As the blood 
flows around the coil it gives off lymph, and from the 
lymph the cells of the gland take certain waste matters, 
which are passed out to the surface of the skin. There is 
also some muscular tissue around the walls of the gland. 

Model of a Sweat Gland. — Take a small rubber tube a foot long ; 
close one end ; tie the half with the closed end into a globular knot ; 
around and between the coils place a network of red cord to represent 
the blood capillaries, as there is a rich supply of these blood tubes 
around the coil. 

The Essential Features of a Gland. — i. Cells lining 
a cavity, the cells having the power of taking something 
from the blood (or lymph). 

2. Blood supply or lymph supply. 

3. A duct or tube to pour out on some surface the 
liquid taken from the lymph. 

4. Nerves to the cells by which their action is controlled. 

5. (Probably) Special nerve centers controlling the 
various glands. The cells of the glands in many cases 
so alter the substances taken from the blood that what is 
produced by the gland differs from anything found in the 
blood. The gland may be said to manufacture the liquid. 

The Relation between Glands and the Blood 
Supply. — The sweat glands, like all glands, are largely 
dependent on the amount of blood supply. In exercising, 
the skin is usually redder from the greater blood supply, 
and at the same time the glands are more active ; for, 
during exercise, and immediately after it, there is more 
waste matter to be thrown out. But the activity of the 
gland is not a mere filtering process, due to the greater 



EXCRETION. 135 

blood pressure. There may be a cold sweat ; i.e. when 
the skin is pale. Here is evidence that the activity of the 
glands is, primarily, due to the nerve impulses from some 
nerve center to the gland cells. 

Sweat Glands are Simple and Excretory. — The sweat 
glands rid the body of certain waste matters that can no 
longer be used. They are excretory glands. In structure 
they are simple glands. 

Distribution of Sweat Glands. — The sweat glands are 
thickly distributed over the whole surface of the body, 
but are especially numerous and large on the palms of the 
hands and the soles of the feet. In the armpits the glands 
are very large. 

The Oil Glands. — The oil glands of the skin are dis- 
tributed over all the surface except the palms of the hands 
and soles of the feet. The oily matter is usually poured 
out around the hairs as they emerge from the skin. It 
serves to oil the hair and the skin, and keep them from 
becoming too dry. 

Composition of Sweat. — Sweat is mostly water; about 
one per cent is solid matter, including salt and certain 
matters which, like the organic waste matter from the 
lungs, easily putrefy, and some oily matter from the oil 
glands of the skin. 

Experiment to show Insensible Perspiration. — Thrust the hand 
into a glass jar, preferably a jar that has been in a cool place. Note 
the moisture that soon gathers on the inside of the jar from the insen- 
sible sweat of the hand. A common fruit jar will do for a small hand, 
but a candy jar is better, having a larger mouth and clear glass. 

Kinds of Perspiration. — Ordinarily the sweat is evapo- 
rated as fast as it is poured out ; in distinction from this 
insensible perspiration, there is the so-called sensible per- 



136 PHYSIOLOGY. 

spiration — when it accumulates enough to be perceptible. 
These are not two distinct kinds of sweat, but it is con- 
venient to distinguish between the perceptible and the 
imperceptible. Sweat varies greatly in its wateriness, and 
hence in the relative amount of solid matter contained. 

The Amount of Perspiration. — There is about one 
quart in twenty-four hours. It varies with: — 

1. Temperature, dryness, and rate of renewal of air. 

2. Condition of the blood; e.g. if watery from drinking 
much water. 

3. Muscular exercise. 

4. Certain drugs — ■ some exciting perspiration, e.g. 
camphor ; others diminishing it, e.g. belladonna. 

5. The nerves exercise great influence on the activity of 
the cells of the gland. 

The Functions of the Skin. 

1. Sensory — organ of touch. 

2. Heat-regulating. 

3. Absorptive. 

4. Protective. 

5. Excretory. 

Next to its excretion, the heat regulation by the skin is 
the most important for our present consideration. 

Regulation of the Temperature of the Body by the 
Skin. — It is a striking fact that, except in disease, the 
temperature of the body varies only a little from 98. 5 ° F. 
in summer and winter, during exercise and rest. The rate 
of heat production varies greatly. The rate of giving off 
heat must therefore vary accordingly. 

The Body gives off Heat. — In considering the regula- 
tion of the body's temperature, we must bear in mind that 
the body is surrounded by air almost always considerably 



EXCRETION. 137 

cooler than itself. The body is, therefore, almost always 
giving off heat. Our clothes do not warm us : we warm 
them, and they keep us from warming the air too fast ; 
i.e. keep us from losing too much heat. Indoor heat in 
winter in the cooler parts of the United States is kept 
at about 70 F. by artificial heat. This air does not warm 
us. We, being about 30 F. warmer, are warming it. 

Ways of Giving off Heat. — The skin gives off heat by— 

1. Radiation: heat is given off in every direction. 

2. Conduction : whatever we touch that is cooler than 
our bodies is warmed. We warm chairs, clothing, etc. 

3. Convection : the air in contact with the skin is warmed 
and rises. Our bodily heat is thus carried off by convection. 

4. Evaporation : the evaporation of the sweat is a much 
more important factor in heat regulation. Any liquid, in 
evaporating, absorbs heat. The cooling effect of alcohol 
or ether on the skin is due to the fact that heat is taken 
from the body in converting the liquid into a gas. 

Experiments in Evaporation. — Let the teacher, with a medicine 
dropper, place a drop of alcohol, ether, or cologne on the back of the 
hand of each pupil. Notice two facts: (1) It produces a cooling 
effect. (2) The liquid soon disappears. To prove that it is not 
merely that the liquid is cool, try the following : Tie a piece of cheese 
cloth around the bulb of a thermometer; dip the bulb into a dish of 
alcohol or ether, and note its temperature (if these are not at hand, 
gasoline serves very well, or even water, though the evaporation is 
slower) ; then lift the bulb out of the liquid, and note any change in 
temperature. The evaporation of the liquid takes heat from the bulb, 
and causes the thermometer to register a lower temperature. We 
sponge the face and hands of a feverish patient to reduce the amount of 
heat. We sprinkle the floor in hot weather, and, by the absorption 
of heat in evaporating the water, cool the air of the room. 

Heat and Exercise. — When we exercise, we produce 
more heat : we sweat more ; more heat is taken from the 



138 PHYSIOLOGY. 

body to evaporate this sweat. If we are not exercising, 
and are in cooler air, we sweat less, and less heat is given 
off. So the temperature of the body is kept uniform. 

This should also be observed : When we exercise, more 
blood is in the skin, and more heat is given off in the 
other ways mentioned; when we exercise less, the skin, 
especially in a cool air, becomes paler; i.e. has less 
blood in it, and heat is economized. 

Distribution of Heat in the Body. — If more heat is 
produced in one part of the body than in the others, the 
circulation of the blood tends to equalize the temperatures 
of the different parts. So, too, if one part is cooled, — 
that is, is losing heat faster than the others, — the blood 
brings heat from other organs to that part. 

For instance, if one holds his hands in the snow, or puts 
a piece of ice on his wrist, the whole blood stream is 
affected. So if the hands and the feet are exposed to the 
cold, it may do little good to have the rest of the body 
covered. A pair of wristers and a pair of leggings may 
often add more to one's comfort than a heavy overcoat. 

Regulation of Bodily Temperature by Food and 
Clothing. — When subject to the influence of cold we eat 
more ; we choose more heat-producing foods, as fatty food- 
stuffs ; we take more vigorous exercise ; we put on more 
clothing, and especially of the non-conducting kinds, — 
woolens. In warmer weather we eat less fatty matter, 
wear less clothing, and are less disposed to exercise 
actively ; we fan ourselves to help get rid of heat ; we 
take ices and cold drinks. For most persons it seems 
better to wear woolen most of the time, as even in summer 
we are subject to sudden changes in the air, and with such 
covering one is less likely to take cold. 



EXCRETION. 139 

The Effect of Wet Clothing. — In getting the clothing wet, the greater 
loss of heat is not from the coolness of the water, but the loss of heat 
in evaporating the water from the clothing. Of course it is desirable to 
put on dry clothing as soon as possible ; but a person in good health is 
not likely to take cold, except in very cold weather, if he continues active 
exercise till he can change the wet garments for dry ones. Children do 
not often take cold from wading in water so long as they are barefooted ; 
but if the shoes and stockings are wet, they are likely to take cold. 

Alcohol and Heat. — The usual effect of q, moderate dose of alcohol 
is to make the person feel warmer. There is more blood in the skin, 
where the nerve endings perceive the effect. More heat is brought to 
the surface and more is given off from the body. A thermometer has 
no " feelings " by which it can be deluded. The thermometer says that 
the body is losing heat. It is as though one were to open a window, 
and as the warm air rushes out by him, were to say, " It is getting 
warmer, 11 not recognizing the loss of heat. There is some heat pro- 
duced in the body by the oxidarton of the alcohol, but this is over- 
balanced by the loss as shown by a thermometer. The fact is, as 
clearly shown by experiment, that alcohol deadens the senses, and 
neither heat nor cold is so readily perceived as before. And this dead- 
ening of the senses also makes one fail to notice fatigue ; hence the 
delusion that the fatigue is gone. 

THE KIDNEYS. 

The Work of the Kidneys. — One important part of the 
work of the lungs, as we have seen, is to throw out carbon 
dioxid. The skin also throws off certain wastes. The kid- 
neys have the special task of excreting a waste product of 
the body called urea. Urea is the nitrogen-containing waste. 

The Parts of the Kidneys. — The kidneys are attached to the dorsal 
wall of the abdominal cavity. The depression in the kidney correspond- 
ing to the stem scar on a bean is called the hilum. From the hilum 
issues a white tube, the ureter, which conveys the urine to the bladder. 

The Blood Supply of the Kidneys. — Entering the kidney along- 
side the ureter is the renal artery, a branch of the aorta, and from near 



140 



PHYSIOLOGY. 



the same point the renal vein returns the blood from the kidneys, and 
pours it into the postcaval vein. Through the kidneys is pouring a 
continuous stream of blood, varying in amount at different times and 
in different conditions. The kidney receives a very large amount of 
blood for its size, as compared with other organs. The flow to it is 
made easy by the fact that the renal arteries are relatively wide and 
short, and take the blood directly from the main current of the aorta. 
The blood leaving the kidney, especially when in full activity, is still 
bright red ; it is probably the purest blood in the body. 



t-.KIDNEY 



Cavity of — 
Kidney 



Urinary Cone 




Vein 



Ureter 
Fig. 52. Cross Section of Kidney. 




Fig. 52 A. The Kidneys and the 
Bladder. Dorsal view. 



Urine. — From the kidney, through the ureter, urine is continually 
passing to the bladder. Urine is mostly water containing urea, salt, and 
various other substances in small amounts. Urea is a waste matter 
brought in the blood. If the kidneys are stopped in their action, urea 
accumulates in the blood, and death soon results ; to just the degree that 
the kidneys fail in performing their duty, just so far must the body suffer. 

Minute Structure and Work of the Kidney. — Examine sections 
of injected and stained kidney. Study the cuts and descriptions of its 



EXCRETION. 



141 



Urinary Capsule 



Artery ~ 



-- Vei 



minute structure. The unit of structure in the kidney is a tube which 
takes material from the adjacent capillaries. The inner end of the tube 
is enlarged into a bail ; this ball is deeply depressed opposite the point 
where the tube leaves it. Into this depression, called the capsule, is 
fitted a globular tuft of capillaries. 

Take a thistle tube (used in the chemical laboratory), let down into 
its bulb a rubber balloon or bag of sheet rubber or cloth, fastening 
the margin around the rim of 
the bulb ; put a little ball of red 
yarn in the depression of the 
bag hanging in the bulb ; have 
two ends of the yarn project- 
ing to represent the artery en- 
tering and the vein leaving the 
capsule. The vein, soon after 
it emerges, breaks up into an- 
other set of capillaries which 
extend around the tube. 
A number of these pri- 
mary tubes unite, and 
many of the common 
ducts open at the apex 
of each of the urinary pyramids, 
emptying their secretion into 
the cavity of the kidney. As 
the blood flows through the 
tuft of capillaries in the capsule 
at the end of the tube, a large amount of water, together with salt and 
some other substances, pass through the thin partition into the cavity of 
the capsule, and thence down the tube. The walls of the tube are thicker 
than, and its cells are different from, those of the capsule. These cells 
take the urea and some other substances from the blood, and pass 
them into the tube to join the more watery material from the 
capsule. 

Comparison of the Skin and the Kidneys. — The kid- 
neys, then, are not very different from the skin. Imagine 
a piece of skin rolled up with the outer surface of the 
skin turned inward. Its glands then would pour their 




Urinary Tube 
Fig. 53. Urinary Cone Enlarged. (Diagram.) 



142 PHYSIOLOGY. 

secretion into a cavity where it might accumulate, instead 
of evaporating as fast as it is poured out. Of course the 
kidneys have a somewhat different work from the skin, 
but in its general plan of working we might say they 
are skin turned outside in. The kidney unit (the tubular 
gland) has branches ; i.e. is compound. The kidney is a 
compound gland of excretion, internal in position. Both 
skin and kidneys excrete a large amount of water, with 
salt and some other matter in common. 

Relation between the Work of the Kidneys and that 
of Skin. — There is a very immediate relation between 
the work of the kidneys and that of the skin. In warm 
weather, and when exercising actively, we perspire freely, 
and the amount of urine is reduced; when we exercise 
less, and especially in cold weather, we perspire less, and 
the urine is more abundant. Cold drives the blood from 
the surface. Consequently more blood goes to the kidneys 
(as well as to the other internal organs), and they throw 
off much more water, though probably little if any more 
urea. The average daily amount of urine is about three 
pints. The quantity is increased by high blood pressure, 
copious drinking, by cold air (driving the blood from the 
skin), nitrogenous food, certain drugs, etc. It is dimin- 
ished by a lowered blood pressure, profuse sweating, 
diarrhea, non-nitrogenous food, and some diseases of the 
kidneys, etc. 

What is the effect of all the processes thus far studied 
on the weight of the body ? 

Reading. — The Skin and Its Troubles, D. Appleton 
& Co. 

Summary. — i. The skin throws off sweat, which is water contain- 
ing waste matter. 



EXCRETION. 143 

2. The tubular sweat glands take the wastes from the lymph which 
soaks out through the walls of the capillaries in the skin. 

3. The activity of the glands is under control of nerves and nerve 
centers, as is also the supply of blood to the skin. 

4. The amount of sweat depends on temperature, exercise, amount 
of liquid food taken, drugs, etc. 

5. The temperature of the body is regulated chiefly by the evapora- 
tion of sweat. 

6. In cold weather we eat more of heat-producing foods, such as 
fats. 

7. The kidneys excrete urea, a nitrogen-containing waste. 

8. There is an intimate relation between the workings of the lungs, 
skin, and kidneys. 

Questions. — 1. Does cutting hair make it grow faster ? 

2. Do cows, dogs, and cats sweat ? 

3. Why is thirst relieved by immersion, even in salt water ? 

4. Why should clothing worn during the day be removed at night ? 

5. How does the body lose heat, except by the skin ? 

6. Why should the blood still be red after passing through the 
kidney ? 

7. What is "skin grafting" ? 

8. Why is it considered a good sign when the skin becomes moist 
during a fever ? 

9. Can food, medicine, or poison be absorbed through the skin ? 



CHAPTER IX. 

FOODS AND COOKING. 

Necessity of Food.- — Thus far we have been studying 
processes by which the body's weight is reduced. We 
have studied the oxidation in the tissues and the removal 
of the wastes. Unless the tissues receive a corresponding 
supply the heat and energy of the body cannot long be 
maintained. 

Food Defined. — Foods are substances that build tissues 
or produce energy without injuring any organ or function of 
the body. Certain substances that do not become part of 
any tissues, nor in themselves produce energy, are useful in 
aiding the processes going on in the body. These may 
be called accessory foods, e.g. condiments ; some accessory 
foods, such as coffee, seem to retard the waste of tissues. 

Foods and Foodstuffs. — Most of our articles of food 
consist of two or more different kinds of materials. For 
instance, milk consists (i) chiefly of water; in this are (2) 
the substance that makes cheese (casein) ; (3) cream, from 
which we get butter (fat) ; (4) sugar, which gives milk a 
sweet taste; (5) salts, such as common salt, lime salts, 
etc. These different materials are foodstuffs. We have 
many kinds of foods, but few foodstuffs, which we find 
occurring over and over again, in various forms, in the 
numerous things we eat. 

144 



FOODS. 145 

Kinds of Foodstuffs. 

1. Proteids (example, casein). 4. Water. 

2. Fats. * 5. Salts. 

3. Carbohydrates (example, sugar). 6. Oxygen. 
Oxygen is by some authors called a food, but it is more 

convenient to treat of it elsewhere. 

The Proteids. — The chief substance in the white of an 
egg is albumen, a typical proteid. Of the many proteids 
some of the more commonly known are casein (the curd of 
milk), gluten (in grains), legumin (in peas and beans), 
fibrin (in blood), myosin (in muscles). Gelatin (obtained 
from connective tissue and bones by prolonged boiling) 
differs considerably from the proteids in composition, but 
may be counted in with them. It is less valuable as a 
food than the true proteids, although in certain circum- 
stances more desirable from the fact that it is very easily 
digested. 

Characteristics of Proteids. — The proteids are — 

1. Composed of carbon, hydrogen, oxygen, nitrogen, a 
little sulphur, and, in some, traces of phosphorus. 

2. Jelly-like, and do not easily diffuse through animal 
membranes (a characteristic to be kept in mind when 
studying digestion). 

3. Coagulable (usually) by heat, acids, alcohol, etc. 

4. Easily putrefy when moist and warm. 

Importance of Proteids. — The proteids are of special 
importance as foods because the most active tissues, muscle, 
nerve, and gland, and the most important liquids of the 
body, e.g. blood and lymph, have proteid as a chief con- 
stituent. Proteid food, therefore, must be taken to make 
good the losses of these tissues during their oxidations. 



146 PHYSIOLOGY. 

Proteid-containing Foods. — The principal proteid- 
containing foods are lean meat, fish, eggs, milk, cheese, 
and some seeds which abound in the vegetable proteids. 

Meat. — Lean meat has about twenty per cent of pro- 
teid, the rest being chiefly water. Beef and mutton are 
more easily digested than veal and pork. It is better to 
buy meat from a very fat animal than from a lean one, for, 
although there is slightly less proteid in the meat from a 
fat animal, this loss is more than made up by the addition 
of fat, which takes the place of water in the meat from a 
lean animal. There is more nourishment in a round steak 
than in tenderloin. 

Fish. — Fish, when fresh, is a good food. Although, 
as a rule, salted meats are less easily digested than fresh, 
salted codfish is a nourishing and economical food. 

Eggs. — Eggs contain considerable proteid, but their 
value as food has been overrated. The yolk has a large 
amount of fat. Although the tgg has all the material 
needed to form a chick, it is not a perfect food for man. 

Milk. — Milk, as we have seen, is an ideal food in that 
it contains all the kinds of foodstuffs, and in the right pro- 
portion for the young mammal. But the proportions are 
not right for the adult. An adult would need four quarts 
and a half daily, and then he would not get enough carbo- 
hydrates (represented in milk by the sugar). The oily 
material in milk is in the form of minute globules, which 
can easily be seen under the microscope. Each of these 
oil droplets is supposed to be surrounded by a thin en- 
velope of albuminous matter, by means of which it is 
enabled to remain suspended for some time instead of 
rising quickly to the surface. Such a mixture of oil in a 



FOODS. 147 

liquid is called an emulsion. When cream is churned the 
albuminous covering is removed and the butter " gathers." 

Cheese. — Cheese is very rich in proteid, much more so 
than lean meat. Yet, as it is rather difficult of digestion, 
we do not use it largely as food ; we regard it more as a 
luxury, while in many parts of Europe it is largely used as 
food, taking the place of meat. It is a cheap food, and 
might well be used more extensively, especially by laboring 
men. When taken with milk it is said to be more readily 
digested. 

Vegetable Proteids. — Peas and beans (dried) contain 
as much proteid (legumin) as meat, and all the cereals 
contain some proteid (gluten). 

Fats. — Fats are composed of carbon, hydrogen, and 
oxygen. The oxygen is small in amount, so these foods 
yield a great amount of energy by the oxidation of their 
carbon (forming carbon dioxid) and hydrogen (forming 
water). The fats most used are animal fats, including 
butter. But some vegetable oils, such as olive and cotton- 
seed oils, are used. 

The Carbohydrates. — Starch and sugar are the chief 
carbohydrates. Starch is used in larger quantity than any 
other foodstuff except water. Sugar is usually regarded 
as a luxury, yet it is an important food. It is quickly 
absorbed. Carbohydrates, like fats, contain carbon, hydro- 
gen, and oxygen. 

Carbohydrate-containing Foods. — The principal car- 
bohydrate-containing foods are the grains, vegetables, 
and fruits. 

The Grains. — The most important grains are wheat, 
corn, rice, oats, rye, and barley. 



148 PHYSIOLOGY. 

Wheat. — Wheat furnishes the principal breadstuff 
among the more civilized nations. It is especially 
adapted to the temperate zones. Taking into consid- 
eration its composition, digestibility, and other charac- 
teristics, it is the most desirable of all the grains for 
civilized man. 

Wheat Flour. — In ordinary white flour nearly all the 
gluten has been removed with the bran or "middlings." 
While wheat or bread made from the whole grain of the 
wheat may support life, one would starve if he attempted 
to live on common white bread alone. It is almost en- 
tirely starch. In the "entire wheat flour" it is claimed 
that all the gluten is retained, only the very thin outer 
husk of the grain being removed. It does not make so 
white a flour, but it is better adapted to use as a food. If 
we use white bread, having thrown away the nitrogenous 
part of the wheat, we need to take more proteid from 
* other sources than if we used the entire wheat flour. This 
is not economy. And it is claimed that the entire wheat 
bread is more wholesome as well as more nutritious. The 
part thrown away has in it phosphates as well as the nitrog- 
enous material. This flour is ground fine so that it has 
not the coarse particles which are in Graham flour, and 
which are in some persons a source of irritation to the 
mucous coat of the digestive tube. 

Corn. — Corn is one of the most nutritious of the grains. 
Although somewhat less readily digested than similar 
preparations of wheat, and, consequently, less desirable 
for indoor workers, it is a fact that, for a given amount 
of money, more nutriment can be obtained in corn meal 
than in any other food known. Corn furnishes food to 
a large part of the human race. 



FOODS. 149 

Rice. — Rice forms a larger part of human food than 
the product of any other plant, being often an almost ex- 
clusive diet in' India, China, and the Malayan islands. 
Rice has a larger proportion of starch, and less of fats 
and albuminoids, than the other 'grains. It is best adapted 
for the food of warm climates. 

Oats. — This grain was first used as food for man by 
the Scotch, but the use has extended and become preva- 
lent in this country. In point of nutrition it is ranked 
higher by some than ordinary grades of wheat flour. 

Rye. — Rye grows farther north than other grains, and is largely 
used for bread in Russia and parts of Germany. It is a valuable food, 
though less nutritious and less digestible than the corresponding prepa- 
rations of wheat. 

Barley. — This grain has wide range of cultivation, and, while in- 
ferior to wheat, is considerably used where other grains cannot be 
raised. 

Potatoes. — Potatoes contain about twenty per cent 
starch, two per cent of proteid, and no fat, the remainder 
being chiefly water, with some useful salts, especially 
potash salts. In spite of its relatively low food value, the 
potato is our most useful vegetable on account of its 
abundance, the ease with which it can be preserved, its 
mild flavor, and the readiness and the variety of ways 
in which it can be cooked. 

Other Vegetables. — The chief nutrient in vegetables 
is starch, though in many the starch is present in small 
amounts. The salts and acids present are of value, and 
care should be observed not to remove too much of these 
salts in cooking. The fibrous matter, cellulose, while in- 
digestible, is of value in adding bulk to the mass of food 
to be digested. Formerly sailors were subject to scurvy ; 



I50 PHYSIOLOGY. 

this is now attributed to a diet of fat and salt meat, to the 
exclusion of fresh vegetables, vegetable acids, etc. The 
disease is avoided by a greater use of vegetables, lime 
juice, etc. 

Fruits. — Many of the fruits, such as bananas and 
apples, have considerable starch and sugar. But the 
fruits are probably more useful to us on account of their 
flavor, due to aromatic bodies, and to their salts and the 
peculiar fruit acids. 

Water. — Water constitutes about two thirds of the 
entire weight of the body. It constitutes the bulk of the 
liquids we have studied, blood, lymph, sweat, saliva, bile, 
etc. Water is the solvent and carrier of all the material 
of the body. Hence we need a large amount of it ; of 
course we must remember that we get a good deal of water 
in most of our solid foods. (See page 357.) 

Rain Water. — Water, as it comes from the clouds, is 
pure. After enough rain has fallen to wash the air, rain 
water is pure, and if caught on a clean roof (especially a 
slate roof) and kept in a clean cistern, it is good drinking 
water. 

Well Water. — Falling upon the earth, the rain water 
soaks down until stopped by some impervious layer, such 
as clay. This water is the supply of our wells and springs. 
It always has more or less earthy matter in solution, and 
is therefore more or less " hard." Unless a large amount 
of mineral matter or some special material is dissolved in 
it, it is, ordinarily, good drinking water. Such water is 
not pure, in the strict sense of the word, but is pure for 
drinking purposes. 



FOODS. 151 

Impurities in Water. — The great source of danger is 
from what are called " organic " impurities. Bacteria will 
not live and grow in pure water. They must have some- 
thing on which. to feed and grow. But in water contain- 
ing a large amount of decaying animal or vegetable matter 
they are likely to abound. And the most dangerous 
sources of contamination are cesspools and sewers. Water 
may be contaminated by such material and not have bac- 
teria in it, but is very likely to harbor such foes. 

Contamination from Cesspools. — The ordinary cess- 
pool is a grave source of danger. Because the well may 
be on higher ground than the cesspool does not give as- 
surance that the water may not be polluted. Often when 
the surface of the ground slopes in one direction, the strata 
underneath may slope in just the opposite direction, and 
the well may be the reservoir into which the cesspool is 
drained. 

Good authorities say that a cesspool should not be 
allowed within a hundred feet of a well. 

Abolish the Cesspool. — But it is better and safer to 
have no cesspool. Where a sewer system is not to be 
had, it is better to allow no great accumulation of such 
material. A deep pit in which a quantity of semiliquid 
matter gathers is not only a nuisance, but a source of 
danger. Privies should have a very shallow pit, or none, 
and should be cleaned often. There should be a little 
dust sprinkled in each day, and occasionally some " chlorid 
of lime " or sulphate of iron. 

Typhoid Fever. - Typhoid fever is now known to be 
usually caused by drinking water. The dejecta of some 
one who has had the disease find their way into the source 
of the drinking water. In many cases this has been clearly 



152 PHYSIOLOGY. 

proved. Of course the dejecta of all such patients should 
be either destroyed or thoroughly disinfected. 

Ice Water. — Although bacteria will not develop in a 
cold place, they are not killed when frozen in water, as was 
formerly supposed. Further,' ice, in forming, does not 
throw out all the impurities, as was formerly stated. So 
it is not safe to drink water formed from melted ice unless 
the water of which that ice was made was good water. 
The ice taken from ponds is not safe. If ice is made 
artificially from suitable drinking water, of course the 
melted product will be essentially unchanged so far as the 
composition is concerned. Water may be cooled by plac- 
ing any ice around it, and we may have the desired tem- 
perature without any admixture of a dangerous element. 

Boiling Water. — When one cannot get good drinking 
water, or when away from home where the water is of 
doubtful purity, it is better to boil the water before using 
it, either as a drink or in preparations of food that are not 
to be thoroughly cooked. It seems to be proved that it 
is better to heat the water twice nearly to the boiling point 
than to boil hard once only. The first heating may start 
the resistant germs into more active life, causing them to 
sprout (so to speak), and a second heating several hours 
later may easily kill them ; whereas it has been proved 
that one hard boiling will not always kill the germs. 

Cautions as to Drinking Water. — Or if one uses tea 
and coffee, it is safer to content one's self with these, and 
not drink much water till that which is safe, as from deep 
wells, can be obtained. 

In hot weather, and especially for those who are engaged 
in hard work, it has been found that a little oatmeal 
stirred in the water is beneficial. 



FOODS. 153 

When overheated, avoid drinking much cold water. Re- 
peatedly rinse the mouth with cool water, and swallow very 
little. This is the way trainers manage a horse at a race, 
and it is sensible to treat a man as carefully. 

Salts. — Salts include many substances besides common 
salt. They aid in the solution of various substances during 
digestion and in other processes. We cannot live without 
salt. 

Lfrne in the form of calcium phosphate and calcium car- 
bonate is essential, especially in the bones and teeth. Iron 
is associated with hemoglobin. 

Necessity of a Mixed Diet. — Our experience, together 
with the results of the experiments on animals, teaches 
that we could not live long if fed on any one class of 
foodstuffs alone. We must take a representative of each 
of the groups. We have noticed that most of our foods 
already contain more than one foodstuff. We so combine 
them as to get suitable proportions. Thus we eat bread 
and butter (a small amount of fat with a large quantity of 
starch and a little gluten), meat and potato, crackers and 
cheese, pork and beans, egg on toast, bread and milk, rice 
and fowl, macaroni and cheese ; they " go well together " 
chiefly because they are complementary. 

Disadvantages of a One-sided Diet. — In order to get 
enough nitrogen from bread alone, one would have to eat 
about four pounds a day ; meanwhile twice as much car- 
bon as is needed would be taken, thus throwing an undue 
amount of work upon the digestive organs. Again, one 
would need to consume about six pounds of meat to get the 
requisite amount of carbon, and six times as much nitro- 
gen as is needed would be taken ; to get rid of this extra 
nitrogen would severely tax the kidneys and liver. 



1 54 PHYSIOLOGY. 

Effect of Cold on Appetite for Fats. — In cold climates 
a large amount of fat is consumed, while in the tropics 
starch is the chief food. Our appetites call for more of the 
fatty foods during the winter season. 

Proper Diet. — While common experience has led people 
to adopt a mixed diet, the proportion of the different- food- 
stuffs is not always what it should be. The proportions 
of the foodstuffs (exclusive of water) may be roughly stated 
as about I part of proteid, I part of fat, 3 parts of carbo- 
hydrates. But this will vary somewhat with the amount 
of work done, and other varying conditions. 

Vegetarians. — The so-called "vegetarians" recognize 
the need of proteid food, and most of them seek proteid in 
eggs, milk, and cheese. But these are animal products, 
and the name " vegetarian " is inconsistent. They are 
merely "anti-meat eaters." If they do actually succeed 
in getting enough proteids from the legumes and the 
grains, the complete digestion of which is difficult, they 
are, as Professor Martin says, to be congratulated on having 
digestive powers that can stand such a strain. That we 
are adapted for using flesh as part of our food is indicated 
in at least two anatomical features: (1) we have canine 
teeth, though not so fully developed as in the carnivora ; 
(2) the intestine in carnivora is very short, that of the 
herbivora very long, but in man intermediate. Neverthe- 
less, it is undoubtedly true that many persons eat too much 
meat. 

Tea. — Tea owes its stimulating effects to a substance 
called thein. This is a stimulant to the nervous system, 
but if not too strong is not followed by a subsequent 
depression. Tea that is too strong is likely to produce 
nervousness and dyspepsia. Boiling the tea leaves also 



FOODS. 155 

brings out the tannic acid that they contain, and produces 
bad effects. 

Coffee. — Coffee owes its stimulating effect to a sub- 
stance called cajfeitiy which is considered identical with 
thein. Coffee acts as a restorative after hard labor, seem- 
ing to retard the wastes of the tissues and food. It is used 
in the army (also in penitentiaries), not as a luxury, but as 
a matter of economy in the matter of food supply. Coffee, 
used to excess, frequently causes palpitation of the heart. 

Malted Milk. — Malted and peptonized milk makes a 
valuable drink for invalids and dyspeptics. 

Cocoa and Chocolate. — Cocoa contains a stimulant 
called theobromin. But unlike tea and coffee, cocoa and 
the preparation from cocoa known as chocolate are true 
foods by virtue of the fat contained. 

Beef Tea. — Beef tea and various beef extracts are very 
beneficial. There is not enough nourishment in them to 
maintain strength without other food. Their nutritive 
value has been somewhat overestimated. Their value is 
probably much more in their stimulating than in their 
nourishing effect. But many of the soups and drinks 
made from these preparations are very beneficial. They 
refresh the tired system wonderfully. If the man who 
feels "fagged out" and takes a drink of liquor to "brace 
him up," as he says, were to take a cup of hot bouillon, he 
would find himself braced up for the time, without any bad 
reaction, or permanent injury to the system, which follow 
the use of alcohol. 

Cooking. — Cooking is designed to make food more 
palatable and more digestible. Some foods, such as eggs, 



156 PHYSIOLOGY. 

are as digestible before they are cooked as after, often more 
so, as they are very frequently badly cooked. But many 
foods in the raw state are unattractive, or even repellent, 
whereas cooking usually develops an agreeable odor and 
taste. Cooking should soften the harder and tougher tis- 
sues, such as cellulose in vegetables, and the connective 
tissue of animal foods. Cooking starch causes the starch 
grains to swell and burst, and makes the starch much more 
digestible. 

Making Soup. — If meat be cut into small pieces and 
put into cold water, and the water gradually warmed, the 
soluble material of the meat may be extracted, and this is 
the principle followed in making soups. 

Boiling Meat. — But if we wish to cook the meat itself, 
the juices should be retained instead of withdrawn. For 
this purpose boiling water is poured over the meat to co- 
agulate the outer layer, and prevent the extraction of the 
juices. 

Baking, Roasting, and Broiling. — The same principle 
applies to baking, roasting, and broiling. The outside is 
subjected to high heat at the beginning of the cooking, 
which forms a layer nearly impervious to the nutritious 
material inside. In these modes of cooking it is very de- 
sirable to reduce the heat applied after the first few min- 
utes, so that the interior may be more gradually cooked ; 
this is, perhaps, especially true in broiling. 

Frying. — Frying, as ordinarily done, is not a good 
mode of cooking ; in fact, is often very bad, as the food is 
frequently penetrated by fat and rendered very indigestible. 
But true frying, that is, by immersion in boiling fat, is a 



FOODS. 157 

good mode of cooking. This coagulates the albuminous 
substance on the outside, keeps in the nutritious juices, 
and prevents soaking with the fat. Often the food to be 
thus cooked is first coated with white of egg, which is 
very quickly coagulated, and helps form a protecting out- 
side crust. 

Reading. — Practical Sanitary and Economic Cooking, 
Abel (Public Health Association); The Science of Nutri- 
tion and the Art of Cooking, Atkinson ; Chemistry of 
Cookery, Williams ; Chemistry of Foods aud Nutrition, 
Atwater (Century Magazine, 1887-88; also Department 
of Agriculture); Eating for Strength, Holbrook; Foods, 
Smith ; Philosophy of Eating, Bellows ; Handbook of In- 
valid Cooking, Boland. 



Summary. — 1 . Food builds tissue and maintains energy. 

2. The simpler constituents of foods are called foodstuffs. 

3. The foodstuffs are water, salts, proteids, carbohydrates, and fats. 

4. Water is essential to life, making two thirds of our weight. 

5. Salts are essential to life. 

6. The chief proteids are lean meat, eggs, cheese, gluten, etc. 

7. The chief carbohydrates are starch and sugar, derived from the 
grains, vegetables, and fruits. 

8. Fats and oils are obtained from plants and animals. 

9. The chief source of impurity in water is from bacteria, which 
thrive when decaying animal and vegetable matter are present. 

10. Boiling water may destroy these germs of disease. 

1 1 . Ice water is not a wholesome drink. 

12. A mixed diet is necessary, as no one food contains all the 
needed material in the right proportions to maintain life well. 

13. Tea and coffee are slightly stimulating, but, if used moderately, 
ordinarily without any bad reaction. 

14. Cooking is to make food more palatable and digestible. 



158 PHYSIOLOGY. 

Questions. — i. Which class of foodstuffs is most expensive? 
Why? 

2. Make a list of all the common foods, naming the foodstuffs in 
them. 

3. Why do we not eat buckwheat cakes and sirup in summer ? 

4. At what price are eggs an expensive food ? 

5. How do flour and potatoes compare in economy at ordinary 
prices ? 

6. Why are foreigners prejudiced against corn ? 

7. Why is broiling better than frying ? 

8. Why do Englishmen in India so generally suffer from "liver 
complaint " ? 




X-RAY PHOTOGRAPH OF HAND 

SHOWING SHOT CARRIED FOR TWENTY YEARS 
(From Recreation, by permission of G. O. Shields.) 



CHAPTER X. 
THE DIGESTIVE SYSTEM. 

The Object of Food. — The tissues are worn out by their 
oxidations. They are built up again by the blood, and 
the blood is renewed by the food. 

All food must be reduced to the liquid condition, if it 
is not already liquid. 

The Digestive Tube. — The chief organ in this work 
of liquefying the food is the digestive tube, or " alimentary 
canal," as it is called. As the food passes through the 
digestive tube it is subjected to various mechanical and 
chemical processes which liquefy it and bring it into such 
a condition that it can be absorbed through the mucous 
lining of the digestive tube and passed into the blood. 

The Work of the Digestive Tube. — To take a special 
instance, a muscle is in part worn out by the oxidation 
during its activity ; to replace the loss suppose we take 
a piece of steak. We cannot substitute this directly in 
the place of the worn-out tissue. In digesting the steak 
we must tear it all to pieces, and reduce it to a liquid form 
by the action of the teeth and by the various liquids from 
the glands along the digestive tube. In short, the muscle, 
as such, must be thoroughly destroyed ; in the liquid pro- 
duced by the digestion of the beef there is no trace what- 
ever of the structure of the beef. But the blood, taking 
this material, builds muscle which can hardly, if at all, be 
distinguished from the original beef. 

i59 



l6o PHYSIOLOGY. 

If the food taken be all ready to build tissue, for exam- 
pie, certain forms of sugar, liquid, soluble, and of the 
proper chemical composition, it will not need to go through 
these changes. 

In order to understand the process of digestion let us 
first turn our attention to the anatomy of the organs of 
digestion. 

The Organs of Digestion. — The organs of digestion 
are the digestive tube and the accessory parts, the masti- 
catory organs, the glands in, and alongside of, the walls 
of the tube. 

The parts of the digestive tube are the mouth, the 
pharynx, the gullet (or esophagus), the stomach, the small 
intestine, the large intestine. 

Brief Description of the Digestive Organs. — At the 

back of the mouth may be seen the soft palate with the 
cylindrical uvula hanging from its center. Beyond this 
is the cavity of the pharynx, which narrows below into 
the gullet, a red-walled, muscular tube, extending along 
the dorsal side of the windpipe, and close to the spinal 
column. It extends the length of the thorax, and then 
passes through the diaphragm and widens into the stomach, 
at the upper left end of the latter. The stomach is some- 
what pear-shaped, with the larger end to the left. At the 
right end it tapers into the small intestine, the first foot 
or so of which is called the duodenum. Then comes a 
long coil of the small intestine, which joins the shorter 
large intestine, ending in the rectum. Just below the 
diaphragm is the dark-colored liver, overlapping a large 
portion of the stomach. Between two of the lobes of the 
liver is the bile sac whose duct enters the duodenum a 
short distance from the stomach. The pancreas is a pink- 



THE DIGESTIVE SYSTEM. 



161 



ish organ of irregular shape lying along the stomach and 
duodenum. "Its duct enters the duodenum at the same 
point as the bile duct. The intestine is held in place by 
the mesentery, a thin fold of transparent membrane folded 
closely around it, and supported from the dorsal wall of 
the abdominal cavity. Between the two layers of the 
mesentery are the branches of the artery supplying the 
walls of the intestines, and the veins that convey the ab- 
sorbed food from the intestine to the liver. 

Digestive Organs of a Cat or Rabbit. — The digestive organs will 
be much better understood if a cat or rabbit be dissected, as the organs 
have essentially the same form and relations. The animal may be 
killed by putting it in a tight box, or under a washbowl with a small 
sponge holding a tablespoonful of ether or chloroform. It may then 
be opened by a slit along the middle line of the ventral surface, from 
the chin to the pelvis. The diaphragm should be noted as forming 
a partition between the cavity of the chest and that of the abdomen. 

To Illustrate the Mesen- 
tery. — To illustrate the rela- 
tion of the mesentery to the 
intestine, suspend the arm in 
a sling made of a handkerchief; 
press the two thicknesses of 
the cloth together just above 
the arm to represent the two 
layers of the mesentery. 

Model of Intestine and 
Mesentery. — A more com- 
plete representation may be 
made as follows : Material : 
piece of large (one inch or more 
in diameter) rubber tubing, 
eight inches long ; sheet of 

thin white court plaster, six inches by twelve inches ; red, blue, and 
white cord. Lay the tube across the middle of the court plaster; gum 
the plaster snugly around the tube ; between the two adjacent layers 




Fig. 54. Cross-section of Abdomen. 



1 62 PHYSIOLOGY. 

of the court plaster, where they meet after passing around the tube, 
lay the three kinds of cord, each frayed out at one end, the frayed ends 
resting upon the tube. Moisten the court plaster and press the layers 
firmly together. The court plaster should now adhere so closely to 
the tube as hardly to be seen, and the two layers should seem as one, 
in which appear the cords representing the arteries, veins, and lacteals. 

The Mouth. — In studying the mouth and contained 
organs, the student should not content himself with mere 
reading, but should carefully examine his own mouth 
cavity by means of a hand glass. We are apt to think 
of the mouth as a cavity of considerable size, as indeed 
it is when fully opened ; but we are not so likely to think 
how completely the cavity is obliterated when the mouth 
is closed. If one notes the sensations from the mouth 
when it is closed, he will perceive that the tongue almost 
entirely fills the space, touching the roof of the mouth, and 
the teeth in front and at the sides. 

The Tongue. — The tongue consists chiefly of muscles, 
extending in different directions, thus giving the tongue 
a variety of motions. The tongue is the chief organ of 
taste, and is therefore (with the sense of smell) the gate- 
keeper of the digestive tube. The tongue has also a keen 
sense of touch (the keenest of any part of the body), and 
so is useful in detecting and removing any food particles 
that may remain on the teeth after a meal. During 
mastication the tongue, with the lips and cheek, keep the 
food between the teeth. When the morsel of food is 
sufficiently masticated, the tongue pushes it back into the 
pharynx to be swallowed. 

The Teeth. — The teacher can usually obtain a lot of 
teeth from the dentist for the asking. These should be 
cleaned before using them in the class. Use pearline 



THE DIGESTIVE SYSTEM. 



163 



or any washing soda. If there be enough time, let each 
pupil make a drawing of one of each of the four kinds of 
teeth ; and it would be well to draw both a front (outer 
surface) and a side view (surface adjacent to another 
tooth) of each of the four kinds. 



Longitudinal Section 



Enamel 



Side View 



Face View 




Pulp Cavity 

Dentine 

Cement 




r — Crown < 



Neck 



>• Root < 




Hole for Blood Tubes and Nerves ' 

Fig. 55. Parts of a Tooth. (Incisor.) 

External Features of a Tooth. — Examine one of the 
front teeth. It has the following parts : — 

1. The crown, the part that is above the gum. 

2. The root, the part that was buried beneath the gum. 

3. The neck, a more or less constricted part, dividing 
the crown from the root ; it is normally at about the sur- 
face of the gum. 

4. A hole at the tip of the root. 

To make a Section of a Tooth. — Let each pupil prepare a longi- 
tudinal section of a tooth as follows : Imbed a tooth in a little sealing 
wax on the end of a spool, cork, or block of wood. With a grindstone 
grind away one half, showing the pulp cavity to the tip of the root as 
in Fig. 55. Make a drawing of the surface thus exposed, naming the 
parts. If human teeth cannot be obtained, almost any kind will serve. 
Let each pupil keep his preparation. 



1 64 PHYSIOLOGY. 

Structure of a Tooth. — i . The pulp cavity, communi- 
cating with a hole in the tip of the root, through which 
the nerve and blood tube entered. 

2. The bulk of the tooth is made up of a substance 
called dentine (ivory). 

3. The crown of the tooth has a covering of enamel, a 
very hard substance. 

4. The root is covered with a bony substance called 
cement. 

The Kinds of Teeth and their Arrangement. — Begin- 
ning at the middle of the front of the mouth, there are (in 
the normal adult) eight teeth in each half jaw : two in- 
cisors, one canine, two bicuspids (or premolars), and three 
molars. 

Dental Formula. — The kinds and arrangement of teeth 
are often expressed by a dental formula, in which the nu- 
merators indicate the upper jaw and the denominators the 
lower, thus : If, C^, PMf, Mf (for one side of the head). 

Incisors. — The crown of an incisor is chisel shaped; 
but the root is flattened in the opposite direction, i.e. at 
right angles to the jaw, instead of parallel to it, as is the 
case with the crown. Look at a skull from which the 
teeth have been extracted in order to see the cavities into 
which the teeth fitted. 

Canines. — The canine tooth has a conical crown, and a 
longer root than the incisor. 

Bicuspids. — The bicuspid has two points. 

Molars. — The molar has a cuboidal crown, and usually 
two or three roots. 

The Milk Teeth. — The thirty-two teeth of the perma- 
nent set were preceded by a temporary set of twenty milk 



THE DIGESTIVE SYSTEM 1 65 

teeth. Because the first set is temporary it should not 
therefore be neglected. Cavities in these should be filled 
and the teeth kept clean. Before the temporary set has 
gone the first of the permanent set appear. The first of 

KINDS OF TEETH Upper TIME OF APPEARANCE 

TEMPORARY SET 

. . Upper 

•"Cisors «:.- _ I 7th Year 

8th « 
Canine '"^^\\mm/ r^" Ilth " 

Bicuspids -.«:; jfjmm Ha 9th " 

tL ^\~ 10th " 

f^, - 6th 

Molars •v : -----fv JiHHfflBI i2th 

•24th 




Lower 
PERMANENT SET 



Fig. 56. TEETH: Kinds, Arrangements, and Times of Appearance. 



these, often called the " six-year molars," are just back of 
the hindermost " milk molars." These should receive 
especial care, as they will never be replaced. Any begin- 
ning of decay in them ought to receive prompt attention. 



1 66 PHYSIOLOGY. 

The Care of the Teeth. — The teeth need careful atten- 
tion. They should be thoroughly brushed at least twice a 
day, on rising and on going to bed. It would be better to 
clean them after each meal also. If a tooth powder, recom- 
mended by a reliable dentist, is not used, a good white 
castile soap will serve well. It is better to use tepid water. 
If the teeth are not thoroughly cleansed the particles of 
food which remain will soon begin to decay. This decay 
is caused by the growth of germs, usually some kind of 
bacteria, and the decay thus begun is likely to develop 
acids which attack the limy material of which the teeth are 
composed. When it is necessary to take acid medicines, 
care should be taken not to let them come in contact with 
the teeth. Sweet substances are very likely to decompose 
and form acids ; so we must clean the teeth after eating 
candies. Toothpicks are useful in removing the larger 
particles. But in using toothpicks care should be taken 
not to dislodge fillings. The teeth should be examined 
twice a year by a dentist, and any cavities promptly filled. 

The Salivary Glands. — The salivary glands make the 
saliva and pour it into the mouth. There are three pair of 
salivary glands — the parotid, just back of the angle of the 
jaw, under the ear ; its duct runs forward under the skin 
of the cheek, and opens on the inside of the cheek opposite 
the second molar of the upper jaw. The submaxillary 
gland lies under the angle of the jaw ; its duct opens under 
the tongue near the front of the mouth. The sublingual 
gland is in front of the submaxillary and empties near the 
same place as the submaxillary. 

Dissection of the Salivary Glands. — The salivary glands of a 
rabbit or cat may be found near the base of the ear and under the angle 
of the jaw by removing the skin from the side of the head and neck. 



THE DIGESTIVE SYSTEM. 



167 



Salivary Ducts in Our Mouths. — If the inside of one's cheek be 
examined by the use of a hand mirror, the opening of the duct from the 
parotid gland may be seen opposite the second molar of the upper jaw. 
It usually looks like a pink and white spot, resembling a wound of a 
bee sting. Sometimes saliva may be seen issuing from it. 

Action of the Salivary Glands. — The salivary glands 
pour into the mouth a liquid which they manufacture from 
materials taken from the blood. In structure the gland 
may be compared to a bunch of grapes, the grapes repre- 
senting the little cavities, with a wall of cells that make 

Mucous Membrane 



Duct of Gland 




Secreting Cells 



Fig. 57. Diagram of a Salivary Gland. (After Landois and Stirling.) 



the saliva. From these cavities the liquid passes into the 
individual duct, represented by the stem of a single grape ; 
many of these unite to form the main stem, which corre- 
sponds to the main duct. A rich network of capillaries 
surrounds the gland ; when the gland is at work it receives 
more blood; the liquid part of the blood (plasma) soaks 
out through the capillary walls and surrounds the gland.' 
it is now called lymph ; from the lymph the gland directly 
obtains its material. 



1 68 PHYSIOLOGY. 

Nerve Control of Salivary Glands. — The glands are 
doubly dependent on nerve control : — 

1. Through the control of the arterial muscles by the 
nerves the amount of blood sent to the glands is regulated. 

2. Nerves also go to the cells of the gland to control 
their activity. When we taste, smell, see, or even when 
we think of, some delicious food the mouth may "water," 
as we say, i.e. the salivary glands are, by reflex action, 
stimulated to activity ; on the other hand, some emotions, 
such as fear, check the flow of saliva. 

Saliva and its Uses. — The saliva is mostly water, and, 
when we are not eating, serves to keep the mouth moist. 
The water of the saliva soaks the food during mastication 
and helps the process of grinding ; it enables us to taste 
by dissolving any food that is soluble ; it further enables 
us to swallow what would otherwise be a dry powder. 
The special element of the saliva, ptyalin, has the power 
of changing starch to sugar. 

Amount of Saliva. — The amount of saliva secreted 
daily is estimated at three pints. Of course the glands 
should be allowed to rest between meals. The habit of 
chewing gum, though supposed to aid digestion, undoubt- 
edly does far more harm than good. During the resting 
period the glands accumulate material for the active work 
of secretion, for there is no sac in which to store the 
saliva, and it must be made as fast as it is needed. 

Character of Salivary Ferment. — " The character of 
action of salivary ferment is further defined by experi- 
ments showing: I, that it is destroyed by boiling; 2, that 
its action is delayed or suspended at a low temperature, 
most pronounced at about body temperature (37 C); 
3, that it acts best in a neutral or in a faintly alkaline 



THE DIGESTIVE SYSTEM. 1 69 

medium, not at all in an acid medium, or in too strong an 
alkaline medium ; 4, that it has almost indefinite power, 
if the product of its own action (sugar) is not suffered to 
accumulate. In all these respects, with the exception 
of the third, the salivary ferment resembles ferments in 
general, which are destroyed by heat, delayed by cold, 
and are limited in their action only by the accumulated 
product of such action." — Waller. 

Enzymes. — Ptyalin is a type ot a group of bodies 
called unorganized ferments, or enzymes. These ferments 
are the agents that produce the peculiar chemical changes 
that are the chief part of digestion. 

Mucous Glands and Mucus. — Besides the salivary 
glands, there are great numbers of simple glands in the 
mucous membrane lining the mouth. These secrete a 
glairy substance called mucus. 

Experiments with Digestive Liquids. — It may be proved by 
experiment that saliva turns starch to grape sugar in an alkaline solu- 
tion and at the proper temperature. Also that pepsin dissolves proteids 
in an acid (hydrochloric) at the right temperature. The proteid is 
turned to peptone, and becomes soluble and diffusible, capable of 
absorption through the walls of the stomach and intestine. We find 
that the different elements of the pancreatic juice can, in alkaline solu- 
tion, and at the right temperature, emulsify fats, turn proteid to pep- 
tone, and convert starch into grape sugar. 

The Pharynx. — The cavity back of the mouth, beyond 
the soft palate, is the pharynx. The pharynx is a funnel- 
shaped cavity, communicating above with the passages 
from the nostrils ; in front it opens into the mouth ; below 
it connects with the windpipe, through the glottis, and 
with the gullet, which, as we have seen, lies just back of 
the windpipe. 



\JO 



PHYSIOLOGY. 



Position of Organs during Respiration. — In quiet 
respiration the tongue nearly fills the mouth. The base 
of the tongue is nearly covered by the soft palate, which 
curves downward from the hard palate, and by the epi- 
glottis projecting upward from below. The glottis is 
open and the gullet is closed. Air enters the nostrils, 
passes along the nasal passages above the hard palate, 
back of the soft palate and epiglottis, through the open 
glottis into the windpipe, and on to the lungs. 



Hard Palate- 




Fig. 58. Diagram, showing the Positions of the Organs «rf the Mouth and 
Throat during Breathing. 

The Process of Swallowing. — When the morsel of 
food is ready to be swallowed the tongue pushes it back 
into the pharynx ; the soft palate is raised to shut off the 
passage into the nasal cavity ; the larynx is pulled upward 
and forward; the epiglottis is pushed down over the glottis, 
or opening of the windpipe ; and the base of the tongue 
extends back over the epiglottis ; thus the air passages, 
above and below, are shut off, and the food passes over 
the epiglottis into the gullet. The muscles of the pharynx 



THE DIGESTIVE SYSTEM. 



171 



also do their part in pushing the food along. As soon as 
the food has passed over the epiglottis, the epiglottis rises 
to its upright position, and the soft palate drops back to 
its place, leaving the air passages again open. 

Breathing and Swallowing. — It is to be observed that 
the food tube and the air tube cross, and that the pharynx 
is their crossing. As we are swallowing only a small 
part of the time, the passageway naturally stands open to 
the air ; and when we swallow, the parts are, by muscular 




Epiglottis, Down 
Gullet, Open 

Glottis, Closed 



Fig. 59. Diagram, showing the Positions of the Organs of the Mouth and 
Throat during Swallowing. 

effort, temporarily adjusted for this work. There is a 
spring switch (to borrow a term from the railway) which 
keeps the track open for the air, which is all the time 
passing ; but when the food comes along, the switch must 
be held open for it until it has passed. 

Structure and Action of the Gullet. —The gullet has 
an outer muscular coat and an inner mucous coat. The 



172 PHYSIOLOGY. 

muscular coat has two layers, an inner with circularly 
arranged fibers, and an outer layer with longitudinally 
arranged fibers. When the food enters the gullet the 
muscle fibers, especially the circular fibers, shorten, and 
by a wave-like action push the mass rapidly along into the 
stomach. The first part of swallowing is voluntary ; but 
after the bolus has entered the gullet the action is involun- 
tary. The mucous lining of the gullet has many mucous 
glands which lubricate the passageway by the mucus which 
they secrete. 

Illustration of Passage through the Gullet. — The passage of the 
food through the gullet may be illustrated as follows : Let several per- 
sons hold a large rubber tube with their hands in contact. Put an egg- 
shaped piece of wet soap in the tube. The first hand is shut and 
pushes the soap along into the part of the tube held by the next hand ; 
this hand now compresses the tube, while the first hand remains clinched ; 
and so, in turn, the object is pushed the whole length of the tube. 

The Stomach. — Just beyond the diaphragm the diges- 
tive tube widens suddenly, forming the stomach; the 
stomach is an oval sac lying just beneath the diaphragm, 
with the large end to the left and the small end to the 
right. The smaller end, by narrowing, becomes the small 
intestine. When the stomach is empty it collapses, as its 
walls are soft and flexible. When distended it may hold 
three pints, or when abnormally distended even more. 

The Coats of the Stomach. — The stomach and intestines have four 
coats, in the following order, beginning at the outside : the peritoneum, 
the muscular, the submucous, and the mucous coats. The muscular 
coat of the stomach consists of three layers, distinguished by the 
arrangement of the fibers, a circular layer, a longitudinal layer, and an 
oblique layer. The mucous lining is somewhat loosely attached to 
the muscular coat by the intervening submucous coat, and when the 
stomach collapses the mucous coat is thrown into folds, usually running 
lengthwise. 



THE DIGESTIVE SYSTEM. 



173 



The Gastric Glands. — In the inner surface of the 
mucous membrane are many holes. These are the mouths 
of the ducts of the gastric glands. If a duct is traced 
inward, it is found to divide into several branches, usually 
two or three. These gastric glands vary somewhat in their 
structure in different parts of the stomach. 

The Gastric Juice. — The liquid secreted by the differ- 
ent glands also varies considerably, but the liquid as a 
whole is called the gastric juice. The gastric juice is 



GULLET 




Fig- 60. Longitudinal Section of Stomach, showing Gastric Glands in Position. 
(Dorsal View. Mucous Coat Unduly Thickened.) 



chiefly water, containing a ferment, or enzyme, called 
pepsin, and a small amount of acid. The amount of 
gastric juice secreted daily has been estimated at from 
five to ten quarts. Of course, we must bear in mind that 
nearly ail of this is again absorbed from the digestive tube, 
and is not a permanent loss to the body. 

Blood Supply of the Stomach. - The mucous mem- 
brane is abundantly supplied with blood tubes, but 
during the time of its rest the blood flow here is 



174 



PHYSIOLOGY. 



Mouth of Gland 



Epithelium 




diminished, and the membrane is comparatively pale. 
But as soon as food is introduced into the stomach the 
blood flow is greatly increased, and the mucous membrane 
becomes red. This blood supply gives the glands the ma- 
terials with which they manufacture the gastric juice. At 

the same time the cells of 
the glands are stimulated 
to action, and the secre- 
tion is poured out rapidly. 
The alkaline saliva also 
aids in stimulating the 
secretion of the gastric 
juice. 

The Work of the 
Gastric Juice.— The spe- 
cial work of the gastric 
juice is accomplished by 
the pepsin, aided by the 
acid; these convert pro- 
teids into a soluble substance, called peptone, which can 
be absorbed through the walls of the digestive tube into 
the blood. 

Rennet and Rennin. — Rennet, used in cheese making, is a familiar 
substance obtained from the fourth stomach of the calf. When milk 
enters the stomach it is curdled ; that is, the casein previously dissolved 
in the liquid milk is coagulated. This curdling, or coagulation, is at- 
tributed to a ferment in the gastric juice called rennin, and it seems to 
be entirely distinct from pepsin. 

Churning Action of the Stomach. — At the same time 
all the food is soaked by the gastric juice, the process being 
greatly assisted by the churning motion of the stomach 
caused by the action of the muscular coat. The food is 
thus gradually reduced to a pulpy mass called chyme. 



Connective Tissue 



Fig. 6 1 • Three Glands of the Stomach 
Cardiac Part. 



THE DIGESTIVE SYSTEM. 1 75 

During the first part of digestion in the stomach the thick 
ring of circular fibers called the pylorus (gatekeeper) around 
the opening of the stomach into the intestine keeps the 
passage nearly closed, leaving a small orifice for liquids 
only. But as the food is reduced to the proper condition 
the pyloric muscles relax and allow the chyme to pass into 
the intestine. And at last any indigestible substances are 
usually allowed to pass. 

Sphincter Muscles. — Such rings of muscular fibers, 
guarding openings, are called sphincter muscles. There 
is a similar one at the anal opening. 

Time of Stomach Digestion. — The time required for 
the digestion of any ordinary meal is from three to four 
hours, though this may be much longer if very indigestible 
substances have been eaten, or if the condition of the body 
or mind is such as to retard the process of digestion. 

Absorption from the Stomach. — Some parts of the 
food that are already digested, or such matters as are sol- 
uble, e.g. water containing sugar, peptone, salts, etc., may 
be absorbed immediately through the walls of the mouth 
and stomach into the blood capillaries. Recent experiments 
show that the amount of absorption from the stomach is 
much less than was formerly supposed ; water, for instance, 
" when taken alone, is practically not absorbed at all in the 
stomach. As soon as water is introduced into the stomach 
it begins to pass out into the intestine, being forced out in 
a series of spurts by the contractions of the stomach." 

Chyme. — The rest of the food, now called chyme, is 
passed on into the small intestine. It is acid, and in a 
liquid or semiliquid condition. Chyme, as it enters the 
intestine, is a mixture of digested, partly digested, and un- 



\y6 



PHYSIOLOGY. 



gastric juice. 



digested materials. Some of the starch has been changed 
to sugar, but only a small part, owing to the short time of 
mastication. The bulk of the starch is unchanged. Some 
of the proteid is already changed to peptone. Part is still 
proteid, while part is in an intermediate stage between 
proteid and peptone. Fat is essentially unchanged, but is 
melted by the heat of the mouth and stomach, and is more 
or less divided into small drops by mastication and the 
movements of the stomach. For instance, in eating bread 
and butter, the melting butter will be finely mixed with the 
bread as it is chewed. The water in the chyme was partly 
taken as such, and partly derived from the saliva and 
There are also present ptyalin, pepsin, 
mucus, salts, and some indigesti- 
ble substances. At intervals the 
sphincter muscles of the pylorus 
relax, and the contractions of the 
stomach send the liquid mixture 
into the intestines by spurts. 

The Intestine. — The small in- 
testine has essentially the same 
structure as the parts of the diges- 
tive tube already studied, namely, 
a mucous lining beset with an im- 
mense number of tubular glands, 
called intestinal glands. These 
secrete a liquid collectively called the intestinal juice, whose 
exact work is not well known, but which may be said to 
complete the work of the other secretions. The intestine 
has also a muscular coat with circular and longitudinal 
fibers. And the muscular coat does the same work of 
mixing the juices with the food and of moving it along. 




Fig. 62. Horizontal Section 
through the Mucous Membrane of 
the Intestine, showing Intestinal 
Glands in Transverse Section. 
(Highly Magnified.) 



THE DIGESTIVE SYSTEM. 



1 77 



Bile and Pancreatic Juice. — Soon after the chyme 
enters the small intestine it has poured upon it two liquids, 
which enter the intestine in one common stream ; these 
are the bile and the pancreatic juice. These juices come 
from two large compound glands, the liver and pancreas, 




Fig. 63. Diagram of Portal Circulation. 

that lie close to the stomach. Their ducts join before they 
enter the intestine into which these juices are emptied a 
few inches beyond the stomach. 

The Portal Circulation. — The liver receives blood 
from two sources, — a branch of the aorta and the portal 
vein. The portal vein is formed by the union of veins 
from the stomach, intestine, pancreas, and spleen. Unlike 



178 PHYSIOLOGY. 

other veins, the portal vein divides and subdivides, forming 
capillaries which ramify through the liver. The blood is 
again collected by veins, forming the hepatic vein which 
empties into the postcaval vein close to the diaphragm. 
From the blood the liver manufactures at least two impor- 
tant substances, — the bile and liver starch, or glycogen. 

Functions of Bile. — The bile is secreted all the time, 
but more actively during digestion. The part made while 
digestion is not going on is stored in the bile sac. The 
functions of the bile are still poorly understood. But the 
following are believed to be a part of its work : — 

1. It is believed to aid in emulsifying the fats. 

2. It is supposed to aid in the absorption of fat. 

3. The bile, to a certain extent, is waste matter ; so the 
liver is an organ of excretion as well as an organ of secretion. 

4. It is found that if, for any cause, the bile is prevented 
from entering the intestine, constipation follows, and the 
contents of the large intestine have a much more fetid 
odor than usual. The bile itself readily putrefies; hence 
it is concluded that the bile has no positive antiseptic 
properties, but in some indirect way retards putrefaction. 

The liver, from its size, ought certainly to be of great 
importance in the body ; it is the largest gland in the 
body, and receives one fourth of the blood. 

The Work of the Pancreatic Juice. — The pancreatic 
juice acts on all the principal classes of foodstuffs : — 

i. A ferment in it called amylopsin acts on starches, 
changing them to sugar, even more energetically than the 
ptyalin of the saliva. 

2. Another constituent of pancreatic juice is trypsin ; 
like the pepsin of gastric juice, this ferment has the power 
of changing proteids to peptones. 



THE DIGESTIVE SYSTEM. 1 79 

3. The pancreatic juice also acts on the fats in two 
ways : — 

(a) It emulsifies them, i.e. the fat is divided into exceed- 
ingly fine drops, each enveloped in a coating of albuminous 
substance. An emulsion can be made artificially by shak- 
ing together water, oil, and white of egg. The shaking 
breaks the oil into fine drops, which would soon gather 
again if no other substance were present; but it is sup- 
posed that the albumen forms a thin coating around each 
droplet, enabling it to remain distinct in the liquid. 

(b) The fats are also acted on chemically by steapsin, 
another ferment of the pancreatic juice ; they are decom- 
posed with the formation of free fatty acids, and thus 
more fully prepared to be absorbed and to build up the 
tissues. These free fatty acids aid in the work of emulsi- 
fying the rest of the fat. 

Review of Digestive Liquids. — Saliva acts only on 
starch, gastric juice on proteids, bile on fats, whereas 
pancreatic juice acts on all three, and, probably, more 
energetically than the above-named liquids. 

Intestinal Juice. — The intestinal juice contains a fer- 
ment, called invertin, which changes cane sugar to dextrose 
which is a variety vmuses 

of grape sugar. flnflM/1 JlMlAflM 




y. 



Acids and Al- 
kalies in Diges- ° p SS of 

tion. — The bile .__ 

and the pancreatic intestinal Glands — ^3l!"pHlo 
juice are alkaline, 

Fig. 64. Mucous Membrane of Small Intestine 

and overcome the 

acidity of the chyme, as the acidity of the gastric juice 

in the stomach overcame the alkalinity of the saliva. 



180 PHYSIOLOGY. 

Summary. — i . The chief work in digestion is to render the food 
liquid, soluble, and in condition to be absorbed and become part of the 
blood. 

2. The digestive system consists of a long tube, through which 
the food passes, being subjected to mechanical and chemical processes 
to liquefy and otherwise make the food ready to become blood. 

3. The teeth grind the food. 

4. The food is soaked and acted on by the saliva, gastric juice, 
intestinal juice, bile, and pancreatic juice. 

5. These liquids are formed from the blood by glands. A gland 
is a structure, usually tubular or saclike, surrounded by capillaries, 
which give off lymph around the gland. The gland cells take part 
of the lymph and form the "secretion," which is usually poured out 
on a surface by means of a narrow tube, or duct. 

6. The salivary glands, pancreas, and liver are compound glands. 
The gastric and intestinal glands are simple. 

7. The first part of swallowing is voluntary. Through the gullet 
the food is pushed by the shortening of the circular muscle fibers. 

8. The liver receives blood from the hepatic artery and from 
the portal vein, but is drained by one vein, the hepatic, which empties 
into the postcaval vein. 

9. Saliva acts only on starch, gastric juice on proteids, bile on 
fats ; pancreatic juice acts on all three of these foodstuffs. 

Questions. — 1. Why does the physician examine the tongue of his 
patient? 

2. What is the "mumps"? 

3. Why is one more likely to choke if he thinks about the process 
of swallowing? 

4. What are the peculiarities of a cow's stomach ? 

5. What is the meaning of biliousness? 

6. Why is there a difference in the length of the intestine in a cat 
and a sheep? 

7. What is colic? 



CHAPTER XI. 
ABSORPTION — DIGESTION COMPLETED. 



Cava! Veins 



Absorption. — The mucous membrane of the small 
intestine is thrown into ridges, but, unlike those of the 
stomach, they 
run transversely. 
Again, while the 
folds in the lining 
of the stomach 
are temporary, 
these are perma- 
nent. They serve 
to increase the 
surface of the lin- 
ing, and to retard 
the passage of the 
food material, and 
so to aid the pro- 



cess of digestion 
and of absorption. 




Fig. 65. Plan of Absorption. 



Capillaries 



Villuses. — 

All the surface 
of the mucous 
membrane of the 
small intestine is thickly beset with little cylindrical pro^ 
jections, like the "pile" on velvet. These projections are 

181 



1 82 PHYSIOLOGY. 

called villuses (or villi). The villuses very greatly increase 
the absorbing -surface of the small intestine. In each 
villus is a network of blood capillaries, and the beginning 
of lymphatic capillaries called lacteals. 

Routes of Different Foods after Absorption. — In the 

villi the largest part of the work of absorption is done. 
The fats are absorbed by the lymph capillaries, or lacteals, 
and the rest of the foods by the blood capillaries. It 
should be carefully noted that nearly all of the foods but 
the fats go at once to the liver, through the portal vein ; 
but the fats are carried by the main lymph duct (the 
thoracic duct) to be emptied into the subclavian vein in 
the neck ; hence do not directly pass through the liver. 

Diffusion, Osmosis, and Dialysis. — If a solution of salt and one 
of sugar are brought into contact, they will gradually mix by diffusion. 
If these two solutions are separated by parchment, they will still diffuse 
through the membrane and mingle. This is osmosis. Since substances 
differ in the readiness with which they pass through a membrane, they 
may be thus separated. Such separation is dialysis, and the membrane 
is called a dialyzing membrane. In the digestive tube the mucous 
membrane represents the dialyzing membrane with blood or lymph on 
one side, and the contents of the digestive tube on the other. Soluble 
materials, such as peptones, sugars, etc., pass through the mucous 
membrane into the blood. 

Absorption a Vital Process. — "The process of osmosis, 
and to a lesser extent of filtration and imbibition, as they 
are known to occur outside the body, were supposed to 
account for the absorption of all the soluble products. 
This belief has now given way, in large part, to newer 
views, according to which the living epithelial cells take 
an active part in absorption, acting under laws peculiar to 
them as living substances, and different from the laws of 
diffusion, filtration, etc., established for dead membranes. 



ABSORPTION— DIGESTION COMPLETED. 



183 



" Unlike sugars and peptones, fats are absorbed chiefly 
in a solid form — that is, in an emulsified condition. 
There can be no question, in this case, of osmosis. It has 
been shown by nearly all recent work that the immediate 
agents in the absorption of fats are again the epithelial 
cells of the villi of the small intestine. The fat droplets 



Right Lymph Vein 




Junction of Thoracic 
^ Duct with Left Sub- 
clavian Vein 



Main Lymph Vein 
(Thoracic Duct) 

- Intestine 



. Lymphatic Glands 



Fig, 66- Lymph Veins — Lymphatics. (.Ventral View.) 



are taken up by these cells, and can be seen microscopically 
after digestion in the act of passing, or rather of being 
passed, through the cell substance. The epithelial cells, 
in other words, ingest the fat particles lying against their 



1 84 



PHYSIOLOGY. 



free ends, and then pass them slowly through their cyto- 
plasm into the substance of the villus." — Howell. 

The. Lacteals and Lymphatics. — While the main work 
of the lymphatics, as we have seen, is the carrying of 
lymph from the tissues of the body generally to empty into 
the veins of the neck, the lymphatics of the intestines 
have another important function. They absorb and carry 
the fatty portions of the digested food into the general 
circulation. During most of the time the thoracic duct 
and the lymphatics of the intestines would hardly be 
noticed because they are filled with the clear lymph. But 
after absorption of fatty matter they are filled with a white 
liquid, called chyle, and are easily seen. 

To show the Thoracic Duct and Lacteals. — To show the thoracic 
duct feed a kitten or puppy on rich milk, and after two or three hours 
kill it as directed on page 27. As soon as you are sure it is dead, 





Lacteal with Valves Capillaries Muscles Epithelium 

Fig. 67. Elements entering into the Structure of a Villus. 

open the abdominal cavity and spread out the mesentery. The white 
lacteals, filled with chyle, will be seen radiating through the mesentery. 
Press on some of these, and it will be seen that they are thin tubes 
filled with a white liquid. They converge toward the place of attach- 
ment of the mesentery to the dorsal part of the abdomen. On the 
dorsal wall of the abdomen, just posterior to the diaphragm, the recep- 



ABSORPTION— DIGESTION COMPLETED. 185 

tacle of the chyle, or the beginning of the main lymph vein (thoracic 
duct), should be found. Trace it anteriorly through the chest along- 
side the aorta to its mouth, near the junction of the left subclavian and 
jugular veins. 

Action of the Villi. — In each villus there are plain 
muscle fibers. When these shorten they squeeze the 
chyle, that has already been absorbed, into the lymph 
tubes of the wall of the intestines, and on into the main 

^——-z^ == -' — ^^rr^^-^Epithelial Covering 



L »gH Jinal Mus- 
cular - 

■ Network 



Fig. 68. Intestinal Villus. 

lymph duct. The chyle cannot return to the lacteal when 
the muscles relax, on account of the valves, similar to 
those of the veins, in the lacteal at the base of the villus. 
Then, when the muscles relax, the lacteal is empty, and 
ready to absorb more of the emulsified fat that we call 
chyle. 

Review of the Digestive Tube. — The whole digestive 
tube may be briefly and roughly described as a muscular 
tube of varying diameter, lined by mucous membrane. 
The muscular coat propels the contents and mixes them 
with liquids ; the mucous coat is beset with glands, making 
liquids, some of which merely soak the food, others act 
on it chemically, while mucus serves to lubricate the sur- 
face. It seems that these myriads of simple glands are 
not enough, so several large compound glands lie along- 
side the food tube and empty their secretions into it by 



1 86 



PHYSIOLOGY. 



ducts ; these supplementary glands are the salivary glands, 
the pancreas, and the liver. 

Length of the Intestine. — The length of the small 
intestine is about twenty-five feet, and of the large intestine 



Parotid Sali- 
vary Gland 



Gullet 



Precaval Vein 
Postcaval Vein 



Hepatic Vein . 

Portal Vein . 

Liver 

Bile Sac 

Bile Duct 



Mesenteric 
Vein 




Sublingual 
Salivary Gland 

Submaxillary 
Salivary Gland 

Lymph Vein 
emptying into 



Left Subcla- 
vian Vein 



Stomach 



... Pancreas and 
Duct 

— Receptacle of 

Chyle 
£» Lacteals 

■■" Mesentery 



Intestine 
Fig. 69. Diagram of the Organs Concerned in the Conversion of Food into Blood. 



five or six feet. The large intestine is not a direct con- 
tinuation of the small ; that is, the small intestine opens 
at a right angle into the large near the beginning of the 
latter, so that there is a short blind end called the cecum. 



ABSORPTION— DIGESTION COMPLETED. 



8/ 



In some animals this is large and has considerable length, 
but in man it is very short. It seems to have been longer 
in man's ancestors, for there is a closed prolongation of 
the cecum, the vermiform appendix. This appendix is 
frequently the seat of serious or fatal inflammation, called 
appendicitis. 



PARTS 

OF 

DIGESTIVE 

TUBE. 


MECHANI- 
CAL PRO- 
CESSES. 


GLANDS. 


LIQ- 
UIDS. 


CHEMICAL 
CHANGE. 


ABSORPTION. 


Material 


By 


Mouth. 


Cutting 

and 

Grinding. 


Salivary. 


Saliva. 


Starch 

to 
Sugar. 






Pharynx. 


RaisingJSoft 

Palate. 
Depressing 
Epiglottis. 












Gullet. 


Food carried 
to Stomach. 


Mucous. 


Mucus. 








Stomach. 


Churning 

and 
Mixing. 


Gastric. 


Gastric 
Juice. 


Proteid 

to 
Peptone. 


Water. ') 
Salts. 1 
Sugars. 
Peptones. J 


Blood 
Capillaries. 


Small 
Intestine. 


Mixing 

and 

Moving 

Food. 


Liver. 
Pancreas. 

Intestinal. 


Bile. 
Pancreatic 

Juice. 
Intestinal 

Juice. 


f Starch to Sugar. 
J Proteid to Peptone. 
1 -p | Emulsified. 
[ ' Decomposed. 


Water. 1 
Salts. 1 
Sugar. 
Peptone. J 
Fats. 


Blood 
Capillaries. 

Lacteals. 


Large 
Intestine. 


Food 
Forced on. 


Mucous. 


Mucus. 




Water. 





Fig. 70. Outline of Digestion. 

The Colon. — The small intestine joins the large near 
the lower right side of the abdomen. The main part of 
the large intestine is called the colon. The last part is the 
rectum. (See Fig. 70 a.) 



88 



PHYSIOLOGY. 



Stomach 
Duodenum . 



The Work of the Large Intestine. — Most of the absorption is 
accomplished in the small intestine ; but as the food passes on into the 

large intestine the work of 
Gullet -f -M digestion and of absorption are 

carried somewhat farther. If 
the residue be not soon ex- 
pelled, there may be absorption 
of some of the results of putre- 
factive changes, and a sort of 
general poisoning of the whole 
body. Hence the great impor- 
tance of regularly and thor- 
oughly emptying the lower 
bowel. The matter thus ex- 
pelled is largely made up of 
indigestible material, with some 
real waste substances. 

Taking up again our com- 
parison of the body and a fur- 
nace, we see that the feces are 
not true waste products, but 
are rather clinkers, or material 
that has not been burned or 
oxidized in the body. The real 
wastes of the body are the car- 
bon dioxid, urea, water, etc., 
that are thrown off by the 
lungs, kidneys, and skin. 
Constipation. — This is a 
very common disorder, and the evils attending it are many. It is well 
known that certain foods tend to bring on such a condition, and that 
other foods have the opposite tendency. Thus, cracked wheat and oat- 
meal are generally considered as somewhat laxative in their effects. 
Fruits generally are laxative. The coarse particles of graham flour are 
irritating to the mucous lining of the stomach and intestines, and for 
many persons stimulate the action of the bowels. But in many persons 
the mucous coat is so sensitive that it cannot bear such irritation. For 
these the "entire wheat flour 1 ' may serve the same purpose. Each 
person should find out by experience what is best for him ; no rules can 




Vermiform 
appendix 



Fig. 70a. Stomach and Intestines. 



ABSORPTION— DIGESTION COMPLETED. 



189 



be laid down that will apply to all cases. But it may be well to know 
what is the usual effect of some of the common articles of food, as per- 
haps some persons may habitually partake of certain articles and do not 
suspect that they are the cause of the trouble. 



LAXATIVE. 

Rolled and cracked wheat bread, 

gems, biscuit, griddlecakes. 
Crackers and mush from flour of 

the entire wheat and graham 

flour. 
Granula. 

Bran gruel and jelly. 
Fruit puddings. 
Fruit pies. 
All fresh acid fruits, including 

tropical fruits, like bananas, 

oranges, lemons, etc. 
Dried fruits. 
French prunes and prunellas, 

eaten raw. 
Stewed dried fruits containing 

hydrocyanic acid, of which 

peaches, plums, and prunes are 

the best. 
New Orleans molasses. 
Rhubarb. 
Onions. 
Celery. 
Tomatoes. 
Cabbage, raw. 
Corn. 
Squash. 
Cauliflower. 
Green peas. 
Spinach. 
Beets, etc. 
Liver. 
Oysters. 
Wild game. 



CONSTIPATING. 

Hot bread. 

White bread. 

White crackers. 

Black pepper and spices. 

Pastry made of white flour and 

lard. 
Bread, rolls, dumplings, etc., made 

with baking powder. 
Cake. 

All custard puddings. 
Salted meats. 
Salted fish. 
Dried meats. 
Dried fish. 
Smoked meats. 
Poultry. 
Cheese. 
Chocolate. 
Cocoa. 
Boiled milk. 
Tea. 
Coffee. 
Coffee made of wheat, corn, bar« 

ley, toast, etc. 
Beans (dried). 
Potatoes. 
Farina. 
Sago. 
Starch. 
Tapioca. 
Rice. 

Raspberries. 
Blackberries. 



190 PHYSIOLOGY. 

Hygiene of Digestion. — A prime requisite for a good 
digestion is a tranquil condition of the whole body, 
especially of the nervous system. We see that the blood 
must be massed in the digestive organs at the time of 
digestion. As there is a limited amount of blood in the 
body, it is evident that if more is sent to one part, other 
parts must at the time receive less. If we try to study 
hard immediately after eating, we are calling the blood 
away from the organs of digestion, and to that extent in- 
terfering with the ,process of digestion. If we exercise 
the muscles too vigorously soon after eating, we call the 
blood to the muscles, and so call it away from the stomach 
and intestines. If, after prolonged study, one is unable to 
obtain sleep, it may sometimes be efficacious and very de- 
sirable to eat a little of some very simple food for the pur- 
pose of drawing off the blood to the stomach, and thus 
relieving the brain. A little muscular exercise may ac- 
complish the same result, or a footbath may be employed. 
For many persons it would probably be better to take a 
simple lunch than to go to bed hungry, although one 
should be careful not to abuse the stomach. 

It is exceedingly difficult to lay down general rules in 
regard to diet. To a certain extent each person must be 
a law unto himself, for what agrees well with one may act 
almost as a poison to another. Moderation should always 
be observed, especially in taking foods to which we are 
not accustomed. 

Solid Foods digest Slowly. — Suppose one were to sit 
down to eat dinner when ravenously hungry. If in such a 
condition one begins with solid food, he is likely to eat too 
fast. Hunger is a demand of the system for food. It 
takes some time for solid food to go through all the pro- 



ABSORPTION — DIGESTION COMPLETED. 191 

cesses of digestion, and be absorbed into the system and 
appease hunger. 

Value of Soup. — But if a soup be first taken, which is 
readily absorbed, the demand of the system will begin to 
be met, and there will not be the same tendency to rapid 
eating. Further, a warm soup stimulates the blood flow 
in the mucous membrane, and thus prepares for more 
thorough digestion. It is more easy after a soup to 
deliberately masticate the solid portion of a meal. 

Desserts. — Dessert and sweatmeats, following a meal, 
are often very helpful by further stimulating the secretion 
of the glands. Nuts, which are not very digestible, are 
beneficial if eaten sparingly. The agreeable taste stimu- 
lates the salivary glands, and the alkalinity of the saliva 
stimulates the gastric glands to increased activity. The 
same may be said of cheese. 

" Cheese is a surly elf, 
Digesting all things but itself. n 

Pie. — The average pie needs some extra help for its 
digestion. Donoghue, formerly champion long-distance 
skater, when asked if he dieted in preparation for a race, 
said he avoided pastry. If the vigorous digestion of a 
man skating for hours daily in zero weather cannot profit- 
ably manage pie, how in the case of sedentary persons ? 
If pie is eaten, it should be masticated with very great 
thoroughness. Undoubtedly most persons would be better 
off if they did not eat puddings and pastries. Fruit is 
best taken before meals, especially before breakfast. 

Hot Drink at Meals. — Hot drink, with a meal, whether 
it be tea or coffee, or simply hot water, is usually bene- 
ficial ; especially to a weak digestion when taken before 
meals. 



192 PHYSIOLOGY. 

The Bad Effects of Imperfect Mastication. — If we 

swallow food before it is thoroughly ground and mixed 
with the saliva, the stomach and other parts of the diges- 
tive organs will require much more time to reduce the 
food to a liquid form. Further, when eating hastily, we 
are very apt to eat too much. Thus we may give the 
stomach a double amount of material to handle, and the 
material may not be half so well prepared as it should 
be. The work thus thrown upon the stomach may easily 
be made fourfold. Of course the organs suffer, and, 
sooner or later, if this treatment is continued, they must 
break down. 

Effect of Repose on Digestion. — Not only mastication, 
but the whole process of digestion, goes on better when 
the body and mind are at rest and in a peaceful and con- 
tented condition, as not only the salivary glands, but all 
the glands, are under the control of the nervous system, 
and are greatly influenced by the condition of the body. 
During a meal, and for a short time before and after, all 
thoughts of one's occupation, and especially all anxiety, 
should be absolutely dismissed from the mind. For those 
whose digestion is not strong, it is especially desirable to 
secure a period of rest after each meal, taking a lounge 
or easy-chair, closing the eyes, and, as nearly as possible, 
closing the mind ; for some, even a short nap is very 
helpful. 

Conversation at Meals. — During a meal there should 
be conversation on topics of general interest. " Chatted 
food is already half digested." 

Deliberation in Eating. — It is said that the people of 
the United States are nervous, and eat, as they do nearly 
everything, hastily. Deliberation in eating adds to dignity 



ABSORPTION— DIGESTION COMPLETED. 1 93 

as well as health, and properly may be considered an 
evidence of culture. 

Time of Eating. — Probably our almost universal custom 
of three meals a day, resulting from experience, is well 
adapted to the needs of our people. Theoretically the 
chief meal should be near the middle of the day, as is the 
custom in the country; for the bodily powers are higher 
than later in the day. But for city people, and others wno 
are very busy in the middle of the day, it is undoubtedly 
better to take the chief meal after the rush of the day's 
work is over, when there is time for a deliberate meal and 
when the mind is free from business cares. For many, too, 
this is the only time when the whole family can leisurely 
meet at the table. 

Eating between Meals. — The stomach should have 
time to rest and prepare for the work of digesting another 
meal. Many find two meals a day sufficient. There are 
some persons, however, for whom it would be better to 
have more meals, with less food at each meal. Meals 
should be regular. 

Amount of Food Needed. — This varies greatly with the 
individual, age, the kind and amount of labor, etc., so that 
no very helpful rule can be given. Each person must find 
by experience what is best for himself. It is the opinion 
of many leading physicians that the majority of man- 
kind eat too much. The fasting enjoined upon some is 
undoubtedly hygienic ; and it would be a valuable lesson 
for more persons to experiment in the line of fasting. 

Errors of Diet. — Sir Henry Thompson, one of the 
foremost authorities in the world on the subject of foods, 
says : " I have come to the conclusion that more than half 



194 PHYSIOLOGY. 

of the disease which embitters the middle and latter part 
of life is due to avoidable errors of diet ; and that more 
mischief, in the form of actual disease, of impaired vigor, 
and of shortened life, accrues to civilized man from 
erroneous habits of eating than from the habitual use of 
alcoholic drink, considerable as I know that evil to be." 

Effects of Alcohol on the Digestive Organs. — While it is 
a popular delusion that alcoholic drinks aid digestion, careful 
experiments show that alcohol retards this process ; the fact 
is that alcoholic dyspepsia is one of the most common effects 
of moderate drinking. The stomach is first acted upon by- 
alcohol; it usually becomes inflamed, and this condition may 
become chronic. The liver, under the influence of alcohol, 
develops an abnormal growth of connective tissue, and takes 
on the characteristic appearance by which it is designated 
as the "hob-nailed liver." 

Reading. — Disorders of Digestion, Brunton ; Indiges- 
tion and Biliousness, Fothergill ; A Plea for a Simpler 
Life, Keith. 

Summary. — i . The hairlike villi lining the small intestine absorb 
the liquefied food. 

2. Sugars and peptones are carried away by the blood capillaries 
and pass through the liver, but the fats are taken by the lacteals into 
the lymph stream to join the blood in the subclavian vein. 

3. Digestion is greatly influenced by the condition of the nervous 
system. 

4. Mastication should be thorough. 

5. Chat at meals is hygienic. 

6. Rest after meals. 

7. Soups and desserts have a physiological justification, though the 
latter often become harmful. 

8. There is a great amount of suffering from intemperance in eating 
as well as in drinking. 



CHAPTER XII. 
NUTRITION. 

Ledger Account of the Body and its Organs. — Through 
the digestive tube and lungs the body receives additions, 
and there is a corresponding loss through the lungs, skin, 
kidneys, and intestines. So a ledger account might be 
kept with the body, and it should balance in the long run, 
since in adult life the weight remains practically constant. 

So we might take a single organ, say the liver, and 
balance its accounts. It receives a large amount of blood. 
To offset what it takes from the blood, it gives to the 
intestines a large quantity of bile, and to the blood it gives 
glycogen. 

It is especially interesting to note the losses and gains 
of the blood as it passes through the various organs of the 
body. A river, flowing past one State after another, will 
take some of the soil of each and deposit some of its 
muddy particles on the banks of each State. Of course, 
the blood is unlike the river, in that it empties into itself ; 
i.e. it is truly a circulation. The blood takes something 
from, and gives something to, each organ as it flows 
through it. From the intestine the blood gets the chief 
part of its new material in the newly digested food. To 
the muscles the blood gives nutritive material and oxygen, 
and receives water, carbon dioxid, and other waste matters. 
The account would be similar with the brain. In the skin 
and the kidneys the blood has great losses and little gains. 

i9S 



196 



PHYSIOLOGY. 



The accompanying diagrams may help in presenting 
the main points in the blood circuit, and the losses and 
gains in its course. 

Blood a Mixture of Good and Bad. — In the common 
blood streams are combined the good and the bad. The 

Capillaries 



Vein 



Artery.— 




Artery 



Vein 



Capillaries 
Fig. 71. Diagram of the Heart and Blood Tubes (Dorsal View). 

newly digested food is received into a current of impure 
blood in the postcaval vein. The blood from the kidneys, 
probably the purest blood in the body, joins the same 
impure stream. From the aorta, red blood, usually called 



NUTRITION. 



197 



pure — the same kind that goes to the brain — is sent 
to the kidneys and to the skin to be purified. Yet, as this 
mixed blood flows through each organ, that organ, so long 
as it is in health, takes from it only what it should take. 



Lung Capillaries 



Pulmonary Vein 




Body Capillaries 

Fig. 72. Diagram of the Circulation, representing the Right and Left Halves separated 
(as they are in reality), showing that the Blood makes but One Circuit. 

Action of Diseased Kidneys. — The kidney takes, 
during health, only the waste matters, leaving the valuable 
nourishing material. But, in disease, the kidneys may 



198 



PHYSIOLOGY 



LUNG 



PULMONARY VEIN 
LEFT AURICLE 



LEFT VENTRICLE 



PULMONARY ARTERY 

RIGHT VENTRICLE 



RIGHT AURICLE 




Fig- 73. Diagram of the Circulation of the Blood. 



NUTRITION. 199 

take out some of the most valuable portions of the nutri- 
ment. Suppose that in a mill, a workman, whose business 
is to shovel out wastes, becomes crazy, and shovels wheat 
or flour out of the mill into the stream below. The dis- 
eased kidney may be said to have become crazy, and in 
the disease called " diabetes " throws out sugar, and in 
"albuminuria" excretes albumen. 

Blood Streams like Water Pipes and Sewer Combined. 

— It is as though the water supply of a city house was taken 
from the sewer; each organ needing a supply of building 
material acts like a filter, taking from the blood what it 
needs, paying no attention to the impurities present, and the 
organs of excretion select the impurities, allowing the useful 
substances to pass on to the places where they are needed. 

A Living Eddy. — Huxley has very aptly compared the 
body to an eddy, whose form remains the same, but whose 
particles are ever changing. 

" To put the matter in the most general shape, the body 
of the organism is a sort of focus to which certain material 
particles converge, in which they move for a time, and 
from which they are expelled in new combinations. 

" The parallel between a whirlpool in a stream and a 
living being, which has often been drawn, is as just as 
it is striking. The whirlpool is permanent, but the par- 
ticles of water which constitute it are incessantly changing. 
Those which enter it on the one side are whirled around 
and temporarily constitute a part of its individuality; as 
they leave it on the other side, their places are made good 
by new comers. 

" Those who have seen the wonderful whirlpool, three 
miles below the Falls of Niagara, will not have forgotten 
the heaped-up wave which tumbles and tosses, a very 



200 PHYSIOLOGY. 

embodiment of restless energy, where the swift stream 
hurrying from the falls is compelled to make a sudden 
turn toward Lake Ontario. 

" However changeful in the contour of it's crest, this 
wave has been visible, approximately in the same place 
and with the same general form, for centuries past. Seen 
from a mile off, it would appear to be a stationary hillock 
of water. Viewed closely, it is a typical expression of the 
conflicting impulses generated by a swift rush of material 
particles. 

" Now, with all our appliances, we cannot get within 
a good many miles, so to speak, of the living organism. 
If we could, we should see that it was nothing but the 
constant form of a similar turmoil of material molecules, 
which are constantly flowing into the organism on the 
one side and streaming out on the other." 

Importance of Renewal of Blood and Lymph. — It 

will be well here to recall some facts noted in connection 
with the study of the blood and lymph. We then learned 
that the lymph (the supply and renewal of which depends 
upon the blood) surrounds the individual cells which make 
up the tissues of the body ; and that, to a certain extent, 
every cell lives an independent life, each taking its nourish- 
ment directly from the lymph around it. The importance 
of an abundant supply of good lymph is now more ap- 
parent. If digestion is not good, or the food be insufficient 
or of poor quality (whether naturally or from being badly 
cooked), good blood cannot be made, and the lymph will 
not be good. The cells are more or less starved, or 
poisoned if wastes are not properly removed, and the gen- 
eral tone of the body will soon be lowered ; for the health 
of the body as a whole depends on the average condition 



NUTRITION 201 

of the cells composing the body, just as the condition of 
any community depends on the average condition of the 
individuals of that community. 

Fat as a Tissue. — As a tissue fat serves as a stored-up 
food. The camel's hump is a well-known instance. In 
some of the savage races fat is stored in a very similar 
hump. But in most persons it is distributed more evenly 
over the body, though there is a tendency to deposit rather 
more over the abdomen. A fat person can endure starva- 
tion longer, other things being equal, than a thin person. 
A layer of fat under the skin serves also as a heat saver. 

Hibernation. — Hibernating animals are fat when they enter upon 
their winter sleep, but are lean when they come out in the spring 
Remaining inactive they have produced very little energy, their only 
motions being a slow and feeble breathing and a correspondingly 
reduced heart beat. They have consumed the fat, using it mainly in 
maintaining the necessary heat. In short, they have burned their fat 
to keep them warm. 

The Hibernation of a Bear. — In one of Captain Mayne Reid's 
stories {The Plant Hunters) we are told how the hunters followed a 
bear into a cave. At the innermost end of this very long cave they 
finally killed the bear. Just at this time they find that their candles 
are all burned out, and they are left in complete darkness, lost in the 
bowels of the earth. Failing to grope their way out, they are at last 
driven to this expedient: With what combustibles they can gather 
together, including their gunstocks and some of the fat of the bear, 
they melt some of the fat, they use the gun barrels for molds, take 
strips of their clothing for wicks, and make two long candles. With 
these they finally light their way out to the upper world. 

Respiration and Oxidation of Candle. — Now we have seen that 
when we burn a tallow candle one of the chief products of the combus- 
tion is carbon dioxid. Another product of the burning is common 
water. If, then, these hunters had left this bear to his winter's nap, he 
would have consumed this fat in the slow process of breathing, and 
it would have given off the same products, as we have proved that two 
of the waste matters of the expired breath are carbon dioxid and water. 



202 PHYSIOLOGY. 

Glycogen. — As stated above, glycogen is formed in the 
liver. This is indicated by the fact that there is more 
sugar in the blood in the hepatic vein than in the portal 
vein, except during digestion. Glycogen is formed by and 
stored in the liver, and is doled out to the tissues. That 
muscles use sugar in their action is indicated in the fact 
that the arteries bring to the muscles more sugar than is 
carried away from them by the veins. As fat is a reserve 
food, so glycogen serves as a temporary carbohydrate re- 
serve. 

Assimilation. — Assimilation is the conversion of blood, 
or lymph, into tissue. It is the last step in the building-up 
process. 

ANIMAL 
PROTOPLASM 



INORGANIC WORLD 

Fig. 74. Animal and Vegetable Protoplasm. 

Nutrition. — Nutrition, in its wider meaning, includes 
all the changes that take place between the reception of 
food and the excretion of waste. On the building-up side 
it includes digestion, absorption, circulation, assimilation. 
On the tearing-down side are respiration (oxidation) and 
excretion. 

Muscular Exertion and Excretion of Urea. — Since 
muscles are the engines of motion, and also are largely 
composed of proteid (nitrogen-containing) materia], we 
would naturally expect that increased muscular exertion 
would increase the excretion of urea (the only nitrogen 



NUTRITION. 203 

containing waste). But experiment shows that increased 
muscular action, such as mountain climbing, hardly in- 
creases the amount of urea excreted. Such work, how- 
ever, does largely increase the amount of carbon dioxid 
excreted. It is thought, therefore, that our energy is 
largely derived from carbohydrate foods and fats, and this 
view is strengthened by the fact that our beasts of burden 
depend chiefly on carbohydrate foods. 



ABSORPTION 
DIGESTION 
ANIMAL FOOD 




VEGETABLE FOOD 



PLANT \ 
1.ANABOLISM/ 



INORGANIC (MINERAL) MATTER 

Fig. 75. Life Processes. 

While increased muscular action does not very per- 
ceptibly increase the amount of urea excreted, an addition 
to the amount of proteid food taken does increase the 
amount of urea. 

Metabolism. — The building-up or constructive pro- 
cesses are included under anabolism, while katabolism 
designates the tearing down or destructive processes. All 
the processes of nutrition, both of building up and tearing 
down, are included in the term metabolism. 

The Indestructibility of Matter. — We are agreed that 
we cannot destroy matter. We may demolish a house, but 
the material is all there. We may burn it, but if we could 
gather the ashes and that part of the smoke and gases 



204 PHYSIOLOGY. 

furnished by the material of the house, the weight would 
all be recovered. 

In the continual wasting away of our bodies there is no 
real loss of matter. Our weight is reduced, but the wastes 
are still part of the earth or air, and are used again. For 
instance, a particle of carbon in the carbon dioxid of the 
expired breath may be taken in through a blade of grass in 
an adjoining field. A cow may eat the grass, and we may 
soon take the very same particle of carbon in the flesh or 
milk of the cow. Or the carbon may be taken by that 
kind of grass called wheat, and become part of the seed 
or grain of wheat, and be made into flour and be eaten as 
bread, and be part of us once more. Or this particle of 
carbon might be carried by the winds to Florida or Cali- 
fornia, and become part of an orange, and come again to 
make part of our bodies. Thus there is a ceaseless round 
of matter into and out of our bodies. The plants furnish 
food for us, and we help to make food for them by the 
wastes of our substance. No one has a monopoly of any 
portion of matter ; it is now ours, now some one else's. A 
particle may pass from one animal to another animal, as 
when we eat flesh or other animal food. But more often 
the wastes of our bodies go to make part of the air or the 
soil, and are then taken by some plant before again becom- 
ing part of our tissues. But we are as unable to destroy 
matter as we are to create it. 

The Indestructibility of Force. — So with energy. We 
cannot create it and we cannot destroy it. We derive our 
energy from the food we eat. And this food we get 
directly or indirectly from the vegetable kingdom. 

An engine gets energy from the combustion of fuel. In 
the growth of the plant under the influence of sunlight the 



NUTRITION. 



205 



plant has stored energy. Now that the wood or coal are 
burned the energy is given out, primarily as heat. But we 
may convert the heat into electricity, the electricity into 
light, or back again into heat if we wish. We get our 
energy from food as the engine gets its energy from fuel. 
This is saying nothing against the superiority of the 
human body, and is not in the least degrading. We are 




n H. 



Solar Energy 



m^ s 



Energy originally obtained from the sun radiated 
by the animal (chiefly) into space as heat, and 
thereby becoming ultimately unavailable 



Fig. 76- Relation of Plants and Animals. 



self-maintaining, self-directing, growing, living machines. 
Still, starvation soon puts an end to our ability to produce 
energy of any kind. 

The Utilization of Energy in the Body and in 
Machines. — Now, it is a well-recognized fact that in very 
many machines only the smaller part of the energy is 
directed to the end sought. Take a common candle. We 
wish to get light from it. But most of the energy of the 
candle is devoted to making heat, which in this case we do 
not desire. In many machines there is great loss from 
friction, from radiating heat, etc. Physiologists tell us that 
the human body utilizes a larger portion of its energy than 



206 PHYSIOLOGY. 

most machines. While energy may fail to be used for the 
desired purpose, it is never destroyed nor really lost. 

CORRELATION AND CONSERVATION OF ENERGY. 

1. The Correlation of Energy. — All kinds of energy 
are so related to one another that energy of any kind can 
be transformed into energy of any other kind. 

2. The Conservation of Energy. — When one form of 
energy disappears, an exact equivalent of another form 
of energy always takes its place, so that the sum total of 
energy is unchanged. 

These two principles constitute the corner stone of phys- 
ical science, and must be learned and kept in mind if we 
would understand the actions of our bodies* and our rela- 
tions to the surrounding parts of the world and the universe 
in which we live and of which we must consider ourselves 
a part. 

Reading. — Foods and Dietaries, Burnet ; Diet in Rela- 
tion to Age and Activity, Thompson. 



Summary. — I . The blood flow is a true circulation ; that is, the 
blood moves in a circuit, being more or less altered by every organ it 
passes through. 

2. The body is an eddy into which particles are constantly entering, 
forming part of it a while, and then passing out. 

3. Fat as tissue is stored food, and consequently stored energy. 

4. Glycogen is a carbohydrate reserve stored temporarily in the 
liver. 

5. Nutrition includes all the processes of the body from the time 
matter enters as food until it leaves as waste matter. 

6. The building-up processes of the body are called Anabolism, the 
tearing down are Katabolism, and both of these are included under 
Metabolism. 



NUTRITION. 207 

7. We can create neither matter nor force, but are dependent on 
food as the engine is dependent on fuel. 

8. We are dependent on the green plants for our food. 

9. The animal body utilizes more of the energy contained in food 
than the engine utilizes from fuel. 

Questions. — 1 . Why is it that some persons eat a large amount of 
food yet remain thin ? 

2. What is meant by "lymphatic temperament" ? 

3. Classify the organs shown in Fig. 73 according to their functions. 

4. What animal is most thoroughly protected from cold by an 
envelope of fat ? 

5. How are plants and animals dependent one on the other ? 



CHAPTER XIII. 

ALCOHOL. 

Fermentation. — If a glass of sweet cider is set in a 
warm place for a day or two, it will probably be observed 
that bubbles of gas are given off and it will now have a 
sharp, pungent taste. The gas is carbon dioxid, and the 
new taste is chiefly due to alcohol, though attributable in 
part to other substances that have been produced and also 
to the loss of sugar. The same change would be likely 
to occur in a moderately strong solution of sugar, and in 
many fruit juices, especially if sweet. Sweet liquids under- 
going this change usually become frothy, or "work," as 
we say, and at the same time acquire a sharp taste. This 
change is due to a process called fermentation. 

Yeast. — Any substance in which alcohol is produced in 
this way is found to contain yeast. Yeast is a microscopic, 
one-celled plant, oval or elliptical in outline, which acts as 
a ferment. Common baker's yeast represents one group 
of these ferments. 

It has been clearly proved that yeast is the cause of 
the above changes, some of the more manifest evidence 
being as follows : (i) Yeast may always be found in liquids 
undergoing alcoholic fermentation. (2) Yeast is killed 
by boiling. If such liquids as have been mentioned are 
thoroughly boiled and placed, while boiling hot, in a 
perfectly clean jar and sealed air-tight, they will keep 
indefinitely without any fermentation of this kind. (3^ 

208 



ALCOHOL. 209 

Yeast added to such sweet liquids hastens, or makes more 
certain, this form of fermentation. 

Yeast cells are not killed by drying. They become dry 
and float as part of the common dust of the air. They are 
still alive, and if they fall into a sweet liquid, especially if 
the liquid is not saturated with sugar, they begin to grow. 
In their growth they break up, or decompose, sugar and 
form at least two substances, carbon dioxid and alcohol. 
Yeast, therefore, is called a ferment, and this change is 
called alcoholic fermentation. A small quantity of yeast 
has the power of changing a large amount of sugar into 
carbon dioxid and alcohol. Then, too, we must remem- 
ber that its growth is so rapid that a small quantity of 
yeast soon becomes a large quantity. 

Ferments. — Besides yeast there are many other ferments 
which, when introduced into liquids, cause various changes, 
i.e. there are many sorts of fermentation. For instance, 
putrefaction is a kind of fermentation of substances con- 
taining nitrogen, during which process offensive gases are 
given off. Most of the ferments belong to a group of very 
simple, one-celled plants called Bacteria. (Yeast is an 
exception, not belonging to the Bacteria.) 

Fermented Drinks. — All the alcoholic liquors are the 
result of alcoholic fermentation of various substances. 
Such liquors may be classed in three groups, — wines, 
malt liquors, and distilled liquors. 

Wines. — The wines are the result of fermentation in 
the juice of the grape or other fruit which is rich in 
sugar. This fermentation was, in all probability, dis- 
covered very early by the human race, for we find it in 
use among nearly all races of men, and accounts of it in 



210 PHYSIOLOGY. 

the early records of history. But it was not until the 
microscope was invented that its cause was known. 

When alcohol accumulates in the fermenting liquid to 
the amount of 14 per cent, it kills the yeast germs; conse- 
quently no natural wine can contain more than this amount. 
Wines are classed as light wines and heavy wines. The 
light wines contain from 5 to 12 per cent alcohol. The 
heavy wines include all wines with more than this amount 
and have had brandy, or other spirit, added to them, having 
from 16 to 25 per cent, or even more, alcohol. 

The Danger in Wine-drinking. — Because some of the 
wines contain a relatively small per cent of alcohol, there 
is a common delusion that there is not much harm in 
drinking them. Let us consider three points regarding 
this. (1) We do not argue or act in the same way in re- 
gard to other substances that are known to be poisonous. 
We do not venture to take small doses of arsenic or phos- 
phorus, saying "Oh! a little will not hurt me." The 
poison is there just the same and will have its effect. 
(2) In small quantities the alcohol in the wine has the 
power to fix the alcohol habit, which is cumulative and 
leads to a desire for more which is almost impossible to 
resist. (3) Because of the very fact that the percentage 
of alcohol in wines is low, enough more of the liquid is 
taken to introduce into the system actually more alcohol 
than is taken by those who drink stronger liquors. 

Wine-drinking cannot be too strongly condemned, either 
on the ground of the effects it directly produces or the fact 
that it leads to the use of stronger liquors. 

Vinegar. — After sweet cider has fermented — or become 
" hard " as we call it — it usually passes on to become vine- 
gar. This change is another form of fermentation, due 



ALCOHOL. 211 

to another kind of ferment. This formation of vinegar is 
likely to take place in any weak solution of alcohol-fer- 
mented liquor. In this fermentation acetic acid is pro- 
duced, hence it is called the acetous fermentation. It is 
interesting to note that the word " vinegar " comes from 
the French vin (wine) and aigre (sharp or sour), as vinegar 
was formerly made by this secondary fermentation of the 
lighter wines. 

Cider. — Besides the ordinary cider obtained from apples 
a cider made from pears, and called perry, is used. It is 
not a good thing to keep sweet cider about the house. It 
is pretty sure to ferment soon, forming alcohol. Hard cider 
contains from 2 to 10 per cent of alcohol. It is not only 
decidedly intoxicating, but experience has proved that 
some of the worst forms of disease result from the habit- 
ual drinking of this alcoholic drink. It also leads to the 
desire for stronger drinks. 

" Temperance Drinks. " — Many well-meaning persons 
use the various preparations called " root beer," perhaps 
without realizing that most, if not all, of them are made 
with yeast and in their preparation undergo fermentation, 
thereby producing alcohol, though not ordinarily in large 
amounts. By giving such drinks (often called "temper- 
ance drinks") to children, an appetite for alcohol may be 
cultivated and the beginning of a terrible habit made. It 
may be well here to call attention to the real meaning of 
the word " habit," that which holds its. 

Malt Liquors. — These are obtained from the small 
grains, especially barley, by soaking the grain and then 
allowing it to sprout. During this process most of the 
Starch is converted into grape sugar. The sugar is 



212 PHYSIOLOGY. 

extracted by boiling, and then, by the addition of yeast, 
alcohol is produced. The chief product is beer, which 
contains from 2 to 5 per cent of alcohol. Hops and other 
substances are usually added. Although the per cent of 
alcohol in beer is low, the effect of beer-drinking is 
marked. As in the case of wine, often the drinker takes 
such enormous quantities of the liquor that the total 
amount of alcohol introduced into the system is large, 
and the effect correspondingly pronounced. In the case 
of many beer drinkers there is apparent a continual state 
of heaviness or lethargy, a sort of perpetual stupefaction, 
which points significantly to the narcotic effect of alcohol. 
It is said on good authority that in the city of Munich it 
is rare to find a sound heart or sound kidneys ; and 
perhaps this is typical of many large cities where beer- 
drinking is so widely prevalent. 

Distilled Liquors. — Distilled liquors, or spirits, are 
obtained from the wines and fermente.d liquors by the 
process of distillation. This process depends on the fact 
that alcohol boils at I73°F., while water boils at 2I2°F. 
The still consists of a large boiler with a large tube rising 
from the top, and this tube extends through, and is coiled 
about in, a reservoir which is kept filled with cold water. 
On heating the fermented liquid in the still up to 173 F., 
the alcohol is converted into vapor. As this vapor passes 
along the coil (known as the worm) the vapor is condensed 
by the cold, and thus the alcohol is separated from the 
water and other liquids, which boil at a higher tempera- 
ture. By distilling wine a large part of the water is left 
behind, and brandy is the result. Whisky is made by 
distilling the fermented grains, especially rye and corn, 
while rum is manufactured by the distillation of fermented 



ALCOHOL. 213 

molasses. Most of the distilled liquors contain from 40 to 
50 per cent of alcohol. By repeated distillation and rectifi- 
cation pure alcohol is obtained. Pure alcohol is not largely 
used, the ordinary commercial alcohol being about 91 per 
cent alcohol. The effects of alcohol on the human system 
will be treated a few paragraphs later. 

Physical Properties of Alcohol. — Alcohol is a clear 
liquid of .79 specific gravity. It boils at 173 F., and does 
not freeze above 200 F., hence is often used in thermome- 
ters. Alcohol dissolves gums and resins, and many sub- 
stances which are insoluble in water. 

Chemical Properties of Alcohol. — Alcohol is composed 
of carbon, hydrogen, and oxygen (C 2 H e O). In composi- 
tion the alcohols (for there are many kinds of alcohol) 
resemble fats. In both there is only a small proportion of 
oxygen to the amount of carbon and hydrogen. For this 
reason both burn with great readiness and produce a large 
amount of heat. Alcohol burns with a nearly colorless, 
but very hot, flame, and does not produce soot ; hence the 
alcohol flame is very useful in delicate work, such as 
watch-making, etc. 

Physiological Effects of a Moderate Dose of Alcohol. 

— A moderate dose of diluted alcohol or ordinary alcoholic 
drink usually has about the following effects, especially 
upon those not accustomed to its use. First, a dilation of 
the blood tubes of the face and of the mucous lining of the 
stomach ; for a very short time a quickened, and perhaps 
more forcible, heart beat ; nervous excitement, shown by 
restlessness and talkativeness ; followed by more or less 
dullness or drowsiness, usually followed by a depressed 
feeling on the next day. 



214 PHYSIOLOGY. 

Effects of Larger Doses of Alcohol. — Larger doses of 
alcohol, or more than what might be called moderate 
drinking, are usually followed by more giddiness, diminished 
sensibility of the skin, partial loss of control of the muscles, 
as shown in speech and gait ; the eyes cease to work in 
harmony, and the person may see double ; nausea is a 
common effect ; and (without attempt to dwell on such 
offensive details) after a time stupor comes on. In such 
drunken sleep the temperature has been known to fall as 
low as 75 F. From this it is very evident how foolish 
it is for one who is exposed to severe cold to drink alco- 
holic liquor to keep himself warm, and the extreme danger 
of such a course. Members of exploring parties in cold 
climates have lost their lives by ignorance of, or disobedi- 
ence to, this well-known rule. In the unconsciousness of 
drunken sleep the full narcotic effects of alcohol are seen. 
And it is very significant that the word by which we 
designate this condition (a word that was applied long 
generations before there was any systematic study as to 
how drugs affect the body), this word — intoxication — 
means 



Alcohol formerly regarded as a Stimulant. — Until late 
years nearly all authorities considered alcohol a stimulant. 
Its effects were apparently such as to rouse the organs of 
the body to a higher degree of activity. But recent experi- 
ments have shown that this effect, which is of a very short 
duration, is not its real characteristic action. In from ten to 
twenty minutes this preliminary excitement begins to abate, 
and is followed by a period of diminished activity. Its 
essential action is that of a narcotic or paralyzing agent. 

Alcohol as a Narcotic. — Many of the later writers who 
have investigated the subject say that alcohol is not a 



ALCOHOL. 21 5 

stimulant, but always a narcotic. The effect on the capil- 
laries is explained as follows : In ordinary conditions of 
circulation, when only a moderate amount of blood is 
needed in any given organ, the circular muscle fibers in the 
walls of the arteries leading to that part are kept shortened 
by nervous impulses sent to them from the nerve centers 
which control them, hence a moderate supply of blood. A 
narcotic has a paralyzing effect on these nerve centers ; 
hence the usual impulses which would have been sent are 
no longer sent, the muscle fibers relax, the artery widens, 
and the part becomes flushed. 

In regard to the effect on the action of the heart, it must 
be remembered that in the first place there are ganglia 
imbedded in the walls of the heart, and that the heart 
tends to beat rhythmically ; second, that there are two sets 
of nerve fibers reaching the heart from without, the sym- 
pathetic, which bring impulses which quicken the activity 
of the heart, and the vagus nerves, which slow its action. 
The sympathetic fibers are accelerators, while the vagus 
fibers retard ; the vagus nerves exert an inJiibitory effect, 
i.e. they act as a brake on the heart's action. If they were 
strongly stimulated, the heart would stop. If impulses are 
not continually sent to the heart along these fibers, the 
heart begins to beat faster, just as a wagon going down 
hill begins to go faster when the brake is taken off. 

The action of the narcotic is to paralyze the nerve center 
from which the restraining impulses normally are sent to 
control the heart. Hence the rapid beat. As to the force 
of its beat there is difference of opinion ; many maintain 
that it has less force than before. 

Under the influence of alcohol the person says and does 
foolish things ; he violates confidence ; he proposes, and 
engages in, rash undertakings ; his higher nerve centers in 



2l6 PHYSIOLOGY. 

the brain are more or less paralyzed; his judgment is 
weakened ; in short, he has lost self-control. 

Alcohol in the Army. — Colonel Alfred A. WoodhulL 
surgeon United States army, says in regard to this matter, 
" I do not think any of our medical officers would seriously 
advocate the issue of alcohol as a measure of health." 

Captain Woodruff, assistant surgeon United States 
army, says, " Spirits can never be used in the army as a 
regular issue ; the practice is thoroughly vicious, and was 
virtually abandoned sixty years ago." 

Dr. Frank H. Hamilton said: "It is earnestly desired 
that no such experiment ever be repeated in the armies of 
the United States. In our own mind the conviction is 
established by the experience and observation of a lifetime, 
that the regular routine employment of alcoholic stimulants 
by men in health is never, under any circumstances, use- 
ful. We make no exceptions in favor of cold, or heat, or 
Yain." 

General Kitchener prohibited all drinks containing alco- 
hol in the Soudan campaign, and of the result a war cor- 
respondent said: "Of one thing I am sure — that the 
mortality from fever and other diseases during the Atbara 
campaign and the final Omdurman campaign would have 
been infinitely greater than it was if alcoholic liquors had 
been allowed as a beverage, or even as an occasional 
ration. 

" The men who grumbled a little when General Kitchener 
emptied out into the street a cargo of Scotch whisky that had 
been smuggled into Berber for sale to the troops, soon dis- 
covered for themselves that the Sirdar was right. Accord- 
ing to official reports nearly four thousand of the soldiers 
now in South Africa are total abstainers." 



ALCOHOL. 217 

Alcohol and Mountain-climbing. — Statistics have been 
collected from mountain-climbers, and a large majority 
testify that alcoholic drinks are injurious or at least not 
helpful. This testimony is all the stronger from the fact 
that it comes largely from Englishmen and Germans, who 
are more likely to have the habit of moderate drinking 
when at home. Mountain-climbing calls for a greater 
expenditure of energy than is probably realized by any 
who have not tried it. Aside from the natural exhaustion 
of such severe exertion, there is likely to be giddiness or 
nausea as a result of the rarefied air. The keeper of the 
house on the summit of Pike's Peak says that such symp- 
toms are almost invariably aggravated instead of being 
relieved by taking alcoholic drink. 

Testimony of a Naturalist. — W. T. Hornaday, author 
of Two Years in the Jungle, who has had years of experi- 
ence as collector in many lands, has the following to say 
as to the use of alcoholic drink : " Above all things, how- 
ever, which go farthest toward preserving the life of the 
traveler against diseases and death by accident, and which 
every naturalist especially should take with him wherever 
he goes, are habits of strict temperance. In the tropics 
nothing is so deadly as the drinking habit, for it speedily 
paves the way to various kinds of disease which are always 
charged to the account of 'the accursed climate.' If a 
temperate man falls ill or meets with an accident, his sys- 
tem responds so readily to remedies and moderate stimu- 
lants that his chances of recovery are a hundred per cent 
better than those of the man whose constitution has been 
undermined by strong drink. There are plenty of men 
who will say that in the tropics a little liquor is necessary, 
'a good thing,' etc.; but let me tell you it is no such 



2l8 PHYSIOLOGY. 

thing, and if necessary I could pile up a mountain of evi- 
dence to prove it. The records show most conclusively 
that it is the men who totally abstain from the use of 
spirits as a beverage who last longest, have the least sick- 
ness, and do the most and best work. As a general rule, 
an energetic brandy-drinker in the jungle is not worth his 
salt, and as a companion in a serious undertaking, is not 
even to be regarded as a possible candidate." 

Is Alcohol a Food ? — Alcohol certainly cannot build up 
muscle or brain or nerve, because these tissues must have 
nitrogen as a constituent element, and alcohol contains no 
nitrogen. 

Undoubtedly the best test of a food is its ability to 
maintain working power. Does alcohol do this ? 

In the above paragraphs are given the results of much 
experiment and observation. Alcohol has been tried in 
the army and navy, on the march and in camp, in hot and 
cold climates, in mountain-climbing, in training for boxing, 
boating, and other athletic contests, and as a result the 
uniform testimony is that it fails to sustain energy, that is, 
as a food it is a failure. Experience shows that men can 
endure more cold and more hard labor without alcohol 
than with it. This has been repeatedly proved in Arctic 
expeditions, in the army and navy, during the hardships 
and exposures of forced marches and deprivations in all 
climates. Neither in hot nor in cold climates is alcohol 
necessary to health, and even its moderate use does 
more harm than good. The explorers in the arctics and 
in the tropics are alike better off without alcohol than 
with it. 

This testimony as to the uselessness of alcohol is all the 
stronger on account of the chemical nature of alcohol and 



ALCOHOL. 219 

the claims made for it. Alcohol contains but little oxygen 
and burns readily and yields a large amount of energy in 
the form of heat. It seems very natural, therefore, to 
jump to the conclusion that it will oxidize in the body and 
produce heat and, perhaps, other useful energy. It does 
oxidize in the body, but, as already shown, it causes the 
body to lose more heat than it furnishes, and the work 
accomplished during the period of its influence is less than 
that accomplished without it. 

The fact of the oxidization of alcohol in the body does 
not necessarily prove that it furnishes the body energy 
that can be utilized, for other substances, everywhere 
recognized as poisons, such as muscarin and carbolic acid, 
are also oxidized in the body. 

It has been claimed that alcohol spares the tissues of 
the body, but it is doubtful if this is true, many experi- 
ments going to show that instead of retarding loss it 
actually causes an increased loss of tissue. 

The fact, then, seems clear that alcohol does not furnish 
the body with available energy with which to carry on its 
daily work. 

On the other hand, we can see how the readiness with 
which alcohol is oxidized in the body is plainly injurious. 
It is. well known that most persons eat more than is needed ; 
in fact, some of the best authorities state that the larger 
part of the ills of the body, especially in later life, come 
from overeating, or as an adage puts it, " one half of 
what we eat enables us to live, the other half enables the 
physicians to live." Now when, in addition to a surplus 
of food, alcohol is also taken, the ready oxidation of the 
latter prevents the complete oxidation of food, and favors 
the accumulation of incompletely oxidized waste products, 
which are very harmful in the system. They clog the 



220 PHYSIOLOGY. 

excretory organs, especially tending to overwork, and con- 
sequently to break down, the liver and the kidneys. 

The Danger of Moderate Use of Alcohol. — Thus far we 
have mainly considered the question whether alcohol is or 
is not useful in supporting the energies of the body. It 
is time to ask another question, What effect does the con- 
tinued use of alcohol have upon the body ? 

No one denies that the use of alcohol may, and often 
does, create an appetite for more, and that this appetite 
frequently becomes uncontrollable. If one eats a sufficient 
amount of bread to-day, he does not, in consequence, crave 
a larger amount to-morrow. But the appetite for alcohol 
grows. The law of its use is the law of increase, until the 
terrible alcohol habit is formed. History is full of ac- 
counts of men who thought they could stop it when they 
chose. The man who says that he can take it or let it 
alone usually takes it. The grip of the alcohol habit is 
well nigh as relentless as the grip of death. 

There is one safe rule : Touch not, taste not, handle not. 

Alcohol as a Poisonous Drug. — Alcohol should be 
classed with the poisonous drugs {e.g. opium, arsenic, chlo- 
roform, belladonna, strychnine, etc.). We know that they 
are very dangerous substances. 

Diseases produced by Alcohol. — The organs most di- 
rectly affected and altered in structure by alcohol are the 
stomach, heart, liver, kidneys, lungs, and nervous system. 
Even moderate drinking may affect any of these organs. 
Tremor of the muscles, especially noticeable in the hands, 
is often observed. This tremor reaches its extreme in the 
terrible disease known as delirium tremens. The heart 
often undergoes fatty degeneration, fat replacing part of 



ALCOHOL. 221 

the muscle. The arteries may undergo the same change. 
The kidneys are disordered, and one form of resulting 
disease is known as Bright's disease. This is often caused 
by moderate drinking. One form of consumption has been 
proved to be due to the use of alcoholic drink. But the most 
positive, and the most serious, effects of alcoholic drinks is 
wi the nervous system, of which more will be said later. 

Predisposition to Disease caused by Alcohol. — In 

many cases where the use of alcoholic drink has not actually 
shown a diseased condition there is marked weakness and 
inability to resist or throw off disease. Drinkers are much 
more subject to sunstroke and to many of the infectious 
diseases. Yellow fever is almost surely fatal to the intem- 
perate. Some forms of pneumonia are more likely to 
attack the intemperate. The insidious nature of alcohol 
and the evil effects of moderate drinking appear when the 
body is attacked by disease. The body is found to be 
undermined and sapped of its strength at the very time 
when a reserve fund of vitality is needed to ward off the 
attack of disease. 

Inheritance of the Effects of Alcohol Drinking. — The 

evil is great enough when seen only in the individual who 
indulges in the drink habit. But the inherited results are 
often worse. First the craving for liquor is often inher- 
ited. This craving may take a mild form, and a person 
of good will power may resist it. But sometimes the 
inherited craving takes the form called dipsomania, in 
which at intervals the craving is so strong that it cannot 
be resisted, while there may intervene considerable periods 
when there is no desire whatever for strong drink. Then, 
too, idiocy, imbecility, and epilepsy are common in the 
children of intemperate parents. 



222 PHYSIOLOGY. 

Alcohol and Poverty. — No one needs to be told that a 
large share of the poverty, everywhere so common, is due 
to the drinking of alcoholic liquors. Much of the earnings 
are frequently spent for liquor ; the man's working capac- 
ity is diminished, his work becomes irregular, and so unre- 
liable that the drinker often fails to obtain employment 
when he is sober. 

The Business Man's View. — Many firms and corpora- 
tions now refuse to hire any one who is known to indulge 
in alcoholic liquors or to frequent saloons. Drinking 
makes men unreliable, and the wise business man will not 
intrust matters of importance — and all business is impor- 
tant — to those on whom he cannot rely. No boy or 
young man can afford to risk his position and his reputa- 
tion by taking a single drink of liquor. 

Alcohol and Character. — Serious as are the effects of 
alcohol on bodily health, and prejudicial as it is to all busi- 
ness prospects and what we usually call success, still more 
fearful are the effects, through the nervous system, on the 
mind and character. Although a later chapter gives some 
attention to this matter, certain phases of the subject may 
be treated here. 

Alcohol and Crime. — Every one knows from observation 
and newspaper reports that much of our daily crime is due 
to alcohol. Without qjoting figures it may be stated that 
carefully collected statistics show that a large per cent 
of the inmates of our jails, reformatories, and penitentia- 
ries are brought to such places through the influence of 
alcohol. 

The Delusive Nature of the Effects of Alcohol. — Alco- 
hol is one of the most delusive substances known to man. 



ALCOHOL. 223 

It seems to give warmth to the cold, strength to the weak, 
activity to the sluggish ; it seems to refresh the weary, 
to quench thirst, and to satisfy hunger ; it seems to rouse 
the mental faculties to a higher pitch of activity, bringing 
forth a greater degree of wit and wisdom than the indi- 
vidual ordinarily displays. It seems to banish fear and 
make the timid brave. 

Let us glance over these seemings and try to get at the 
real facts in the case. 

The feeling of increased warmth after taking alcohol is 
due to the greater amount of blood in the skin where the 
nerve endings are affected, or to the deadened sensibility 
to cold, or to both ; test by the thermometer shows that 
the body's temperature is lowered. 

After taking alcohol a person may feel stronger ; actual 
test of strength shows diminished muscular power. 

Fatigue seems to have been done away with because 
sensibility is blunted ; any form of drowsiness would 
produce the same result. 

Hunger appears to be satisfied through the action on 
the nerves of the stomach ; but the body's need of food 
has not been satisfied. Thirst may seem to have been 
allayed ; but only soon to return intensified. What usu- 
ally passes for wit, under the influence of alcohol, is ordi- 
narily the silliness of the tipsy ; under this influence the 
person overestimates his wisdom, while others can easily 
see that his judgment is warped. He may fear danger 
less than before, but it should not be called bravery ; he is 
less sensible of danger, and he has become rash or even 
reckless. 

In all these cases sensibility is lowered, and the nerve 
centers, especially the higher centers, have become more 
or less paralyzed. For a short time the blood and the 



224 PHYSIOLOGY. 

brain run riot, the reins of judgment having been thrown 
overboard. Power has not been gained, but control has 
been lost. 

Alcohol is not the "elixir of life," it is the "fountain of 

death." 

The Danger of using Alcohol. — The danger is especially 
great where there is a latent hereditary tendency to in- 
ebriety or insanity. Many individuals, on finding a drug 
which exhilarates and banishes the weight of oppression 
by which they are borne down, are tempted beyond their 
power of resistance, even though they know that the reac- 
tion will bring them into a worse condition than the one 
from which they sought relief. The pressure of modern 
life, and the intensity of the struggle for a living, brings 
about a condition of nervous strain that is fraught with 
great danger. Every thinking man should see that to use 
alcoholic drink for the relief of such a condition is like 
venturing out in a boat above the Falls of Niagara — he 
knows not when the rushing, mighty power will gain the 
mastery and dash him to destruction. 

Reading. — The Temperance Teachings of Science, Pal- 
mer; The Foundation of Death, a Study of the Drink 
Question, Gustaf son ; The School Physiology Journal. 

Summary. — i . Alcohol is a very dangerous drug and should be 
used only when prescribed by a physician. 

2. Athletes avoid alcohol when training. 

3. A large per cent of crime is due to alcohol. 

4. On account of its rapid absorption alcohol is a quick recuperative 
after collapse. 

5. In small amounts alcohol is oxidized in the body, producing 
energy. 

6. Alcohol usually lowers the temperature of the body through the 
increased skin circulation. 



ALCOHOL. 225 

7. It is especially dangerous to take alcoholic drink when exposed 
to severe cold, as in Arctic explorations. 

8. In the army alcoholic drink as a regular ration did more harm 
than good ; hence was discontinued. 

9. More hard work can be endured without alcohol than with it. 

10. The precise effects of alcohol are hard to determine. But every- 
body knows that its effects are generally bad. 

1 1 . Alcohol is now classed as a narcotic and not as a stimulant. 

12. Alcohol deludes by deadening the senses, giving the false 
impression that heat and strength have been gained and fatigue 
banished. 

13. If thirst seems quenched, the deception is revealed by the fact 
that the thirst quickly returns intensified. 

14. Alcohol is not a true food. 

Questions. — 1 . Why do some persons think that alcoholic drink 
makes them warmer ? 

2. What do statistics show as to "expectation of life" among 
abstainers and alcohol users ? 



CHAPTER XIV. 

EXERCISE AND BATHING. 

How Exercise is Beneficial. — The full significance of 
the benefits of muscular exercise could not be understood 
when we studied the muscles, and before we had studied 
the blood and its work in the tissues of the body generally. 
Now we can comprehend how exercise stimulates the cells 
to activity, renews the lymph around the cells both by 
quickening the blood flow and by pressure on the lymph 
tubes ; how the glands of excretion are set to work more 
actively, and the more rapid blood stream brings away the 
material to be thrown out. 

Exercise for General Health. — Exercise is not merely 
for the muscles. It quickens the action of the whole body 
by increasing cell activity. It helps clean out the system 
and clear the brain as well. We read Blaikie's admira- 
ble book, How to Get Strong, and learn not merely to 
strengthen the muscles, but how to get strong to do the 
work we have to do daily, how to feel well every day, how 
not only to do our work, but to do it gladly, and with a 
little extra good cheer that may radiate from us and in- 
spire others. We have no right and no need to carry the 
sour visage of a devitalized body. Good health is attain- 
able, and ought to be attained, by nearly all. Attention 
must be paid to the laws of our being. It takes some 
effort, mental as well as physical, to adopt and observe 

226 



EXERCISE AND BATHING. 227 

regular hours for exercise and relaxation and to be careful 
in diet. 

Nature's Rewards and Punishments. — But nature 
rewards for obedience by the delight of a healthy body ; 
and she never forgets and never forgives, nor fails to pun- 
ish every violation of every one of her laws. Nature makes 
no threats beforehand. She does not even tell us her 
rules. But we may find what they are by careful obser- 
vation. 

Exercise prolongs Life. — Many men would live longer, 
feel vastly better, and do greater good in the world if they 
would take regular and systematic exercise or recreation 
(and this should be, literally, re-creation). It is a short- 
sighted policy to say, " I cannot afford the time." Not to 
take time for exercise is to mortgage one's future. Lord 
Derby says, " He who does not take time for exercise will 
have to take time for illness." The latter half of every 
person's life ought in many respects to be by far the most 
productive of good. But many cut off this half, or render 
it less productive through breaking down in health as a 
consequence of violating the laws of hygiene. Thus one 
defeats his own ends in life, and robs the world of the debt 
he owes it, that of returning to it, in his riper years, some- 
thing for the help it gave to him in his early years while 
he had not yet reached the fullest mental maturity. It is 
sad enough that so magnificent a structure as the human 
body must perish and become part of the common clay. 
But it is infinitely more sad to think that it has not fulfilled 
its purpose when the end comes in what should be mid- 
career. Each of us should leave the world better than he 
found it, and our ability and opportunities for doing this 
increase as we reach middle life. 



228 PHYSIOLOGY. 

Forms of Exercise. — In selecting the kind of exercise 
the old lines fit well : — 

" In whate'er you sweat, indulge your taste ; 
The toil you hate fatigues you soon, 
And scarce improves your limbs." 

Of course this does not mean that a boy should refuse 
to saw wood because he dislikes it, and spend all his time 
playing ball. But for older persons, especially those of 
sedentary occupation, exercise that exhilarates is far more 
beneficial than that which is not enjoyed. One may take 
a walk and carry all his cares and anxieties with him, but 
he is not likely to think of such matters when playing 
tennis with a good opponent. Whether it be horseback 
riding, cycling, boxing, boating, skating, or other form of 
exercise, choose, whenever a choice is possible, that which 
you thoroughly enjoy. Exercise should be taken out 
doors whenever possible. The gymnasium is a substitute 
in bad weather. 

Games of School Children. — Most of the games of 
school children are excellent kinds of exercise. Cases 
have been reported of injury from excessive skipping the 
rope. But in moderate degree it is a good exercise. Tag, 
snowballing, racing, the various games of ball, jumping, 
hopping, and other games may be played on the school 
grounds. 

Tennis. — Tennis is a fine game, and suitable for girls 
as well as boys. It has the great advantage over baseball 
that it does not require a large ground (which often means 
going some distance from the school grounds or from 
home). Two can make up a game, and a little time can 
be better utilized than with the games requiring more 
players. The exercise, too, is more evenly distributed. 



EXERCISE AJVD BATHING 229 

There is no long waiting, as in some games, but a constant 
interchange of play, active but not severe, with practically 
no danger of injury. 

Baseball and Football. — For those who can pursue 
the more vigorous games of baseball and football they are 
admirable, and should not be objected to because occa 
sional injury comes from them. No vigorous exercise is 
wholly unattended by risk, though it is usually slight when 
the proper care is used. All these games calling for great 
activity and strength develop manly qualities in boys, and 
do much to make them active, fearless men, men who in 
time' of danger have not only strength and endurance, but 
well-trained muscles, cool heads, and brave hearts, men 
who know what to do and how to do it in an accident, as 
at fires, upsetting of boats, etc. A few strong, cool-headed 
men, by their presence of mind, often stop a panic and 
save many lives when there is an alarm of fire, which often 
proves false. The Duke of Wellington said that it was 
on the football fields of Eton and Rugby that the battle 
of Waterloo was won. 

Boxing. — Boxing is a splendid exercise. It calls into 
play nearly every muscle of the body. Many pieces of 
apparatus in a gymnasium are for the especial purpose 
of working certain muscles. But a set of boxing gloves 
may be said to contain a whole gymnasium. Many kinds 
of work in a gymnasium are likely to be overdone, espe- 
cially if not under the direct supervision of a good director. 
One may overlift or overstrain himself. But in boxing 
there is little tendency in this direction. Boxing makes 
one quick on his feet, trains to quick movements of the 
arms, trains the eye, keeps the body in an erect position, 
and especially develops the muscles of the legs and back. 



230 PHYSIOLOGY 

Boxing brings out the chest and shoulders. It develops 
the "wind," and keeps one in constant action. It teaches 
control of the temper more than almost any form of exer- 
cise. It develops a degree of self-reliance that is worth 
much. Instead of developing a tendency to become in- 
volved in quarrels, it prevents getting into such disgraceful 
affairs. The man who knows that he can defend himself 
when it becomes necessary is far less likely to pay serious 
attention to idle bluster" and slight provocation than one 
not so trained. And it may prove valuable to know how 
to defend one's self from the attack of a ruffian, or bully, 
or drunken brute, or other infuriated animal. The cool- 
ness of head, the quick judgment, and prompt action of 
a trained boxer frequently saves one from serious injury, 
and adds not a little to personal comfort. Like tennis, 
boxing calls for little apparatus, little space, and only two 
persons. In many places where ordinary gymnasium 
work is out of the question, boxing is available. It is 
indeed a "manly art," and the doctrine taught in Tom 
Brown's School Days at Rugby is as wholesome as can be 
given to boys to make them strong and active, to give 
them physical and moral health. 

Bicycling. — This is an excellent exercise, as it is in 
the open air and exhilarating. There is danger of over- 
exertion, and it is bad for one to yield to the temptation 
to make long runs. There is danger of overtaxing the 
heart. The handle bar should be adjusted to allow a 
fairly upright position. The saddle should be such as not 
to sustain the weight on the perineum. 

Exercise for Middle-aged Men. — For men in middle life, in most 
cases, milder exercises are preferable, such as shooting, fishing, and 
horseback riding. Every person should have some form of exercise 
that takes him into the open air daily. The English are more given 



EXERCISE AND BATHING. 23 1 

to their "constitutionals" than their American cousins, and are the 
better for it. Doubtless if we paid more attention to these matters, 
we should lose something of our national reputation as a " nervous 
people." English women are noted walkers, and do not seem to pride 
themselves on the smallness of their feet. The signs of the times 
would appear to show that we are improving in this respect. Probably 
Americans make too much use of street cars. Walking is the cheapest 
exercise, and every one can afford to take it. For those who can 
afford it horseback riding is admirable. As Dr. Holmes expressed it, 
" saddle leather is in some respects even preferable to sole leather ; 
the principal objection to it is of a financial character.*' Lord Palmer- 
ston said "the outside of a horse is the best thing for the inside of 
a man.'" Perhaps livery bills would prove cheaper and more agreeable 
than doctors' bills. 

"Taking Cold." — So long as one is actively exercising, 
he is not likely to take cold. But if one rests in a cool 
place, especially when he is warm, he is, as we all too well 
know, likely to take cold. As we saw when we were 
studying the circulation of the blood, the application of 
cold to the skin causes the arteries (through reflex action) 
to become smaller. Thus when resting in a cool place the 
skin becomes pale and cold. 

During a " cold " there is fever. The regulation of the 
heat by the skin is interfered with. At the same time it 
is often noticeable that the urine is more abundant than 
usual. As cold may lead to fatal lung disease, so it may 
be the beginning of some disease of the kidneys that may, 
in the end, bring fatal results. 

Diarrhea. — Diarrhea, which is a catarrhal condition of the intes- 
tine, may follow, or be associated with, a cold, and as a result of this 
the process of absorption is often largely checked. There is a great 
increase in the secretion of mucus by the mucous glands in the intes- 
tinal wall. As the various liquids of digestion are all taken from the 
blood, it is evident that if some returns are not soon made, the system 
must become bankrupt. It is, then, more easy to understand the ex- 



232 PHYSIOLOGY. 

cessive weakness and feeling of utter prostration that we experience 
during an acute attack of diarrhea. We can now understand where all 
the material comes from to make the profuse discharges, especially 
after we have ceased eating for some time. 

It is a significant fact that diarrhea is usually called " summer com- 
plaint. 1 ' During the warm summer nights we are tempted to go to 
sleep with very little covering over our bodies. But it almost always 
grows cool before morning. The common summer diarrhea is, in 
many cases, due to bacteria taken in food ; but, on the other hand, may 
be simply a " cold in the bowels." 

Bathing. — One purpose of bathing is to cleanse the 
skin. For this purpose warm water is best, and it is de- 
sirable to use soap, especially on those parts which are 
especially exposed to contamination, such as the hands, 
the feet, the armpits, and groins. 

Cold Baths. — Another important function of bathing 
is to act as a systemic tonic. For this purpose cold bath- 
ing is better, but this should not be too long continued, 
and must be followed by brisk friction to give the skin a 
ruddy glow. For this kind of bath a tub is not necessary, 
and hardly desirable. The water may be quickly applied 
by means of a sponge, and the body thoroughly rubbed 
with a coarse towel. The whole process should be com- 
pleted very quickly, especially if the room be not warm. 

Bath Mits. — Instead of the sponge and the ordinary 
form of towel, it may be found more convenient to use 
bath mits made of Turkish toweling. These are easily 
made, and are somewhat more convenient, as thus friction 
may be more readily applied than with a towel, which is 
apt to slip in the hand. The two hands may be used at 
the same time, and the whole time of the bath need not 
exceed two or three minutes. At the beginning of a bath, 
cold water should be applied to the head and face. 



EXERCISE AND BATHING. 233 

Time for Bathing. — For students, or others who do 
not take a great deal of vigorous exercise, which keeps 
the skin active, this. means of keeping the skin active is 
especially valuable. The use of warm water for cleansing 
seems best adapted (for busy people) to the time of going 
to bed. But the best time for the cool bath is on getting 
up in the morning. 

Warm Baths vs. Cold Baths. — Prolonged warm baths 
are debilitating, and probably increase a tendency to take 
cold, whereas cold bathing is one of the very best means 
of fortifying against cold, and especially against the ten- 
dency to take cold on slight exposure. For most persons 
a cool sponge bath, on rising, will act as a most excellent 
tonic ; but if it seems to produce neuralgia, it should be 
used with caution. 

Exercise of Arterial Muscles. — We have learned that 
the blood supply to any organ is regulated by the action 
of the plain muscle fibers in the walls of the small arter- 
ies. Now, when we are subject to changes in temperature 
these muscles get exercise, and one writer has well called 
the cold bath the gymnastics of the plain muscle fibers, 
and we can understand how the system can be trained to 
adjust itself to cold, and enabled to avoid "taking cold" 
so frequently. 

Habit of Cold Bathing acquired Gradually. — There 
are undoubtedly many persons who do not profit by cold 
bathing, but probably many of these would soon adapt 
themselves to it by beginning with tepid water and gradu- 
ally using cooler. To stand stripped in a cold room, of 
course, is not a safe thing to do. And the great secret of 
the benefit that may be expected from the operation, as 
most people are situated, is to be very brisk, the whole 



234 PHYSIOLOGY. 

process occupying only a few minutes. Many are opposed 
to cold sponge bathing, and condemn it without reserve, 
when, probably, they have never really given it a fair trial. 
Let it be repeated, with emphasis, that for students it is 
one of the very best means of preserving health. 

Reading. — Baths and Bathing (Health Primers, D. 
Appleton & Co.). 

Summary. — i. Exercise stimulates the activity of all the organs, 
by promoting cell activity and assisting excretion. 

2. Exercise should be in the open air as much as possible. 

3. Exercise is more beneficial when it exhilarates. 

4. Exercise should be taken regularly. 

5. Warm baths are best for cleansing, and a good time is at bed- 
time. 

6. Cold baths stimulate the circulation of blood in the skin, and 
serve as a tonic to the whole system. Just after rising is a good time 
for the cold bath. 

7. The cold bath fortifies against taking cold. 

Questions. — 1. Should exercise be carried to the point of fatigue ? 

2. How can one avoid taking cold after exercise ? 

3. Do girls need exercise as much as boys ? 

4. What is the condition of the body during a " cold " ? 

5. How may a cold be caused ? 

6. How may a cold be cured ? 

7. How may a cold be prevented ? 

8. Why do some persons take cold so much more readily than 
others ? 

9. Why does the same person take cold more readily at one time 
than at another ? 

10. How often should a person bathe ? 

1 1 . What hour is best for sea bathing ? Why ? 



CHAPTER XV. 
THE BRAIN. 

The muscles are the executive organs ; but the seat 
of the will is the brain. 

If models of the brain can be obtained, they should 
be carefully studied. If not, the accompanying figures 
may be used in their stead. 

The Coverings of the Brain. — There are two readily 
distinguishable coats of the brain, the dura mater, a tough 
membrane, adhering more or less closely to the inside 
of the skull ; and the pia mater, next to the brain, a much 
thinner membrane, traversed by blood tubes, and dipping 
down into the grooves between the convolutions of the 
cerebrum. 

The Parts of the Brain. — The larger and upper part 

of the brain is the cerebrum ; below and back of this is 
the smaller cerebellum ; the part of the spinal cord within 
the cranium is generally reckoned as part of the brain. 

The Cerebrum. — The cerebrum consists of two lateral 
hemispheres, separated by a deep median groove. The 
surface of the cerebrum is in irregular ridges, the con- 
volutions. The outside of the brain consists of gray 
matter, whereas the outside of the spinal cord is white. 
The inner part of the brain is white, and the two halves 
are connected by a broad band of white matter, which 
consists of many white fibers. 

235 



236 PHYSIOLOGY. 

The Cerebellum. — The cerebellum is much smaller 
than the cerebrum, and has fine transverse ridges and 
grooves in place of the convolutions of the cerebrum. It 
is also of a deeper color, a reddish gray. The cerebrum 
overlaps the cerebellum so that the latter could not be 
seen from above if the whole brain were laid bare. But 
in the lower animals the parts of the brain are more in 
a series, one behind the other, and in a line with the 
spinal cord. 

The Spinal Bulb. — The enlarged beginning of the 
spinal cord, often called the medulla oblongata, is the 
spinal bulb. It is white like the rest of the cord. 

The Brain of a Cat or Rabbit. — The brain of a cat or rabbit may 
be exposed by first mounting the specimen as directed for showing the 
spinal cord (see p. 27). After removing the skin from the upper part 
of the head, the bone should be cut away between the eyes with a pair of 
bone forceps. • Cautiously working backward, the whole of the brain 
may be unroofed. Great care must be exercised, for here we have one 
of the softest tissues of the body lying very closely beneath one of the 
hardest. It is possible to do this with a strong knife, but the bone 
forceps save a great deal of hard work. The bone must be broken 
away bit by bit. To remove the brain, it will be necessary to cut 
through the tough dura mater that covers it. 

Removing this, there will be found an inner covering, the pia mater, 
a membrane richly supplied with blood tubes, from which the brain 
gets its nourishment. After the dura mater has been removed, the 
anterior end of the brain may be gently lifted with the handle of the 
scalpel and the under surface studied, following the description of 
the cranial nerves. 

Preservation of the Brain. — The brain may be studied while it 
is fresh, but it is more easily handled after it has been hardened. Lay 
the brain in weak alcohol, about 25 per cent. It should rest on a layer 
of cotton, otherwise it may be very much flattened by its own weight, 
Later transfer it to 50 per cent alcohol, and then to 75 per cent. When 
it is well hardened, it may be sliced with a sharp scalpel as directed. 
A better and quicker method is to use a solution of alcohol and forma- 



THE BRAIN 237 

iin as follows : 95 per cent alcohol, 60 parts ; 2 per cent formol, 40 
parts. The liquid need not be changed if used in sufficient volume. 

The Brain of the Rabbit {Alcoholic Specimen). — The brain of 
a cat or dog is better, being larger. Take a brain well hardened, and 
review the parts as named above. It is very desirable to have a speci- 
men in which the arteries have been injected. 

1. Press down the cerebellum to see the deep groove between it and 
the cerebrum. The thin membrane covering the brain and dipping 
into the groove is the pia mater. 

2. Press down the spinal bulb and tear away the pia mater where 
it passes from the cerebellum to the spinal bulb. Note, between the 
bulb and the cerebellum, a space covered by a thin membrane. Cut 
through this membrane ; the cavity is the fourth ventricle of the brain. 
Observe the two ridges bounding the sides of the fourth ventricle. At 
the point of their divergence, observe the opening of the central canal 
of the spinal cord. 

3. Gently separate the cerebral hemispheres, and note the trans- 
verse band of white fibers connecting them. 

4. Examine the under surface of the brain, and find the roots of the 
cranial nerve. 

The Cranial Nerves and their Functions. — i. The 

olfactory lobes extend forward under the fore part of the 
cerebral hemispheres. They are the nerves of smell. 

2. The optic nerves, or nerves of sight, join each other 
before reaching the brain. Only the first and second pairs 
of cranial nerves directly enter the cerebrum. 

3. Back of the optic nerves, near the middle line, is the 
third pair of nerves. The third, fourth, and sixth pairs 
of cranial nerves control the muscles of the eyeballs. 

4. The fourth pair extend up on each side into the 
groove between the cerebrum and the cerebellum. 

5. Back of these is the larger fifth pair, the trigeminal. 
This pair supplies part of the face, and sends branches to 
the teeth. It is the nerve affected in neuralgia of the 
face. Besides being the nerve of sensation for most of the 



238 



PHYSIOLOGY. 



head and face, this nerve has motor fibers which control 
the muscles of mastication. Unlike the other cranial 
nerves, the trigeminal resembles the spinal nerves in 
having two roots, one sensory, the other motor. 



Optic 2 

(Sight) 



Eye Motor, ..—-£%, 

3,4,6 '■"■■£% 

o 



Auditory, 8 
(Hearing) 



Vagus, 10 



Hypoglossal, 
12 (Tongue 
Motor) 



I, Olfactory 
(Smell) 




7, Facial 
(Face 
Motion) 



, Glosso- 
pharyngea 



V MI, Spinal 
Accessory 



Fig. 77. The Base of the Brain, showing the Origin of the Cranial Nerves. 



6. Back of and inside of the fifth pair is the sixth pair. 

7. The nerves of the seventh pair are larger, and are 
farther back and outward. These are the facial nerves, 
and control the muscles of the face and the facial expres- 
sion. 



THE BRAIN. 



239 



8. Close to the seventh are the eighth, or auditory- 
nerves. 

9. The ninth, tenth, and eleventh arise close together, 
farther back and well up on the sides of the spinal bulb. 
The ninth supplies the back of the tongue and the pharynx, 
and is called the glossopharyngeal nerve. It gives the 
sense of taste from the base of the tongue. 

Cerebrum 




Spinal Bulb 



Fig. 78. Vertical Section of Brain. 



10. The tenth pair, or vagus nerves pass down out of 
the brain cavity, give off branches to the pharynx and 
larynx, and are distributed to the heart, lungs, and stomach. 
The vagus nerves are so widely distributed that their func- 
tions cannot be briefly stated. (See pp. 66 and 67.) 

n. The eleventh pair arise in part from the spinal 
cord outside of the cranial cavity, enter the skull, and pass 



240 PHYSIOLOGY. 

out again to supply certain muscles of the neck and 
shoulders. 

12. The last pair of cranial nerves, the twelfth, arise 
near the middle line of the spinal bulb. This pair supply 
the muscles of the tongue, and are called the hypoglossal 
nerves. 

Brain composed of Two Hemispheres. — It will be 
observed that the brain, like the spinal cord, consists of 
two lateral parts. Cutting sections of the brain length- 
wise and crosswise shows that the outer part is made up 
> of gray matter and the inner part of white matter. The 
gray matter is composed of cells essentially similar to those 
of the spinal cord, while the white 
matter of the inner part is composed 
of white fibers like those of the outer 
part of the spinal cord, or like the 
nerves. 




Brain Convolutions and Intelli- 

Fig. 79. Pyramidal Nerve gence. — The brain of the rabbit has 

Cells, found principally in the x i . • .i .i . r L\ 

Gray Matter of the Brain. feWei " Convolutions than that of the 

cat, and is nearly smooth. In gen- 
eral, the lower animals have fewer convolutions, and the 
lower races of mankind have smoother brains than the 
higher races. In the earlier stages of development man's 
brain is smoother, but with growth the convolutions 
appear, and increase in number with the growth of the 
brain. As we know that intelligent action depends on 
the gray matter of the surface of the brain, we infer that 
to accommodate its increase in the brain case it is thrown 
into folds, as the surface of the lining of the intestines is 
increased by folds and villi. 



THE BRAIN. 



241 



Gray and White Matter of the Brain. — The gray 
matter of the convolutions of the adult human brain is 
about one fifth of an inch thick, the larger part of the 
brain consisting of the white matter. Sections will show 
that there are several masses of gray matter in the brain 
deeper than the con- 
volutions. These _^a&^^ -Gray Matter 

are the ganglia of 
the brain. The 
white fibers inside 
the bram connect 
the gray matter of Ganglia 
the convolutions 
and these ganglia 
with all parts of 

the body through Fig. 80. Diagram of the Brain, showing the Spinal 

the spinal cord. 




Cerebrum 



Cord, Ganglia, and Course of the Fibers. 



Neuroglia, — The brain consists of nerve cells and nerve 
fibers, bound together and supported by a form of connec- 
tive tissue called neuroglia. 

The Cerebrum and its Functions. — If the cerebral 
hemispheres are removed from a frog, he will sit up about 
as before, but seems to pay little attention to what is going 
on around him. If placed on his back,, he will turn over 
and sit up. If pinched, he may jump away, and may show 
that he can see by avoiding anything that may come in his 
way. If placed in the water, he will swim, and if he swims 
against anything that he can climb upon, will do so and 
remain quiet. If placed on a board, and the board be 
slowly tilted, he will move along and keep his equilibrium, 
climbing over the end of the board if necessary to keep his 
balance. If left alone, he will not move, but will die in 



242 



PHYSIOLOGY. 



his tracks, though he will eat food if it is put in his mouth. 
He seems to have lost the power of willing to do anything, 
or what we call the power of volition. He originates no 
action. 

A Pigeon with Cerebrum Removed. — A pigeon with 
its cerebrum removed acts in about the same way. It 
remains quiet, stupid, paying no attention to ordinary 




lerve 
2d Spinal Nerve 



Fig. 81. Diagram of the Cranial Nerves and Sense Organs. 



events. A sudden loud noise may cause it to start. If its 
tail be pulled, it moves forward to regain its balance. If 
thrown in the air, it flies for a distance. It swallows food 
placed in its mouth, but would starve surrounded by food. 



THE BRAIN. 243 

Placed on its back, it will right itself, but it does not show 
the usual degree of intelligence and will power. 

Function of the Cerebral Cortex. — " Experimentally, 
we learn that after the removal of the cortex (gray matter) 
an intelligent animal is reduced to the state of a non-intellr 
gent automaton, responding indeed to stimuli, internal as 
well as external, but failing to interpret the significance of 
present events in accordance with bygone experience. A 
brainless dog is stupid ; he may see a bone in front of his 
eyes without showing signs that he knows the meaning of 
a bone or the use to which it may be put ; he may hear the 
crack of a whip, but he no longer shows signs of fear, 
for he does not remember its sting ; his former purposeful 
behavior has entirely disappeared ; in short, he has lost 
memory and judgment." — Waller. 

The Center of Sensations itself Insensible. — The 

gray matter of the outside of the brain is the central organ 
of intelligent sensation and motion. The functions of voli- 
tion, of consciousness, of intelligence, seem to reside in, or 
rather to depend upon the activities of, the cells of the 
gray matter of the convolutions of the cerebrum. This we 
have learned from experiments on the lower animals, and 
from accidents and disease in the case of man. All sensa- 
tion seems to be in the gray matter of the convolutions of 
the cerebrum, and yet it is itself insensible ; it may be cut 
and cause no sensation. But when the nerve impulses 
from the various parts of the body reach the gray matter 
of the cerebrum they rouse the cells here to an activity 
that gives us what we call sensation. It is never a sensa- 
tion until it reaches this part and is properly interpreted. 

Crossed Control of the Body. — While each hemisphere 
mainly controls the muscles of the opposite half of the 



244 



PHYSIOLOGY. 



body, it also, in part, has control of its own side. Paralysis 
of one side (hemiplegia) is due to injury of the opposite 
cerebral hemisphere. 

Location of Brain Functions. — Much has been learned 
of late years as to the location of special functions in the 
brain. Many of the motor centers have been determined 



CENTRAL FISSURE 
MOTOR AREA /' 
L.'E G 




FISSURE OF SILVIUS 



Fig. 82. Location of Brain Functions. 

in the following manner : In some of the lower animals 
the brain has been exposed, and on stimulating certain 
portions with an electric current the movements that fol- 
lowed were noted. In monkeys, " particular movements 
of the arm, forearm, hand, and thumb can be produced by 
excitatiou of particular spots, almost as regularly as definite 
notes can be sounded on a piano by touching particular 



THE BRAIN. 245 

keys." In the case of man we infer that there is a similar 
location, and many cases of accident and disease have 
helped in locating the functions. But these areas are not 
sharply defined. 

Left Hemisphere Better Developed. — The " speech 
center" is in the left hemisphere; the right eye and ear, 
which connect with the left brain, are better developed 
than the left, and in general the left hemisphere seems 
superior (in right-handed persons) to the right. 

Location of Centers of Sensation. — It is not so easy 
to locate the centers of sensation as those for motion. For 
we can see the resulting motion, but a sensation can only 
be felt by the individual in whom it occurs. Still, some of 
the sensation centers have been located, and it is likely 
that in time we shall know much more on this subject. 
The accompanying diagram shows some of these centers. 

The Functions of the Cerebellum. — The cerebellum 
is the center for regulating the actions of the skeletal mus- 
cles. When we walk or run, or even stand still, a number 
of muscles must act, and act in concert. The nerve im- 
pulses originate in the cerebrum, but the cerebellum is the 
center for harmonizing the action of these various muscles, 
or coordinating them. When the cerebellum has been re- 
moved from a pigeon the bird flutters, and, while possess- 
ing the power to move, does not seem capable of any 
regular and orderly movement. There is no loss of intelli- 
gence, no paralysis. Of course, in this experiment there 
is great disturbance of the system, and perhaps too much 
is inferred from it. 

Functions of the Spinal Bulb. — The spinal bulb is the 
connection between the spinal cord and the brain. The 



246 PHYSIOLOGY. 

bulb may be said to be that part of the spinal cord which 
is within the cranium. It is enlarged, hence its name, 
spinal bulb. From it arise all the cranial nerves except 
the first five pairs. The spinal bulb is also the center for 
the control of respiration, of circulation, of deglutition, and 
perhaps for many other processes. 

Brain Work and Brain Rest. — Sleep is not merely 
rest for the body ; it should be complete rest for the brain. 
In so far as there are dreams, it would seem to indicate a 
partial activity ; that is, incomplete rest. The brain worker 
especially needs plenty of sleep ; excellent authorities say 
at least eight or nine hours. The brain, like the muscles, 
needs exercise, and it also needs regular periods of rest. 
If a nerve cell is not kept active by the passage of nerve 
impulses through it, it usually atrophies, and may de- 
generate. 

Sleeplessness. — Intense brain work, without sufficient 
sleep, is likely to lead to sleeplessness, as when one has 
some subject of special study in hand and either will not 
or cannot throw it off. Perhaps inventors are as prone to 
this sort of trouble as any one class of men. Keeping the 
blood continually in the brain, or in any organ, is likely to 
lead to a permanent congestion or inflammation that may 
cause serious, if not fatal, results. 

Fatigue. — It is stated that brain workers need more 
sleep than those who work chiefly with the muscles. Fa- 
tigue of the voluntary muscles is much more a matter of 
nervous than of muscular origin. When one is completely 
" tired out," as he would say, if his mind can be aroused, 
as by some excitement, he will be found able to expend a 
good deal more muscular energy. So, too, many persons 
of slight muscular build, but of great "will power," are 



THE BRAIN. 247 

able to do more work with the muscles than others with 
larger muscles and less will. During fatigue the cell bodies 
are found to decrease in size, but there is no discernible 
change in nerve fibers as a result of fatigue. 

Control of Mind. — But the brain worker should not 
only be able to sleep regularly and long enough ; he ought 
to be able to throw off his mind any subject, and take rest 
while he is awake. If one allows himself to think about 
mental work while eating, the process of digestion will not 
go on well. 

Habit of Resting the Brain. — The student should ac- 
quire the power and cultivate the habit of having, so far 
as possible, regular hours for work, and of completely 
throwing aside his work and worry at stated times. In 
seeking recreation it is well to choose that which will 
necessitate giving the attention to something entirely dif- 
ferent from the daily work. For this reason chess may 
be no real recreation for the student, while a game of 
tennis, boxing, or other competitive exercise is likely to 
accomplish this very desirable object. A walk may put 
the muscles into play, but if the mind is still intent upon 
the line of work maintained throughout the day, the exercise 
may prove of little benefit. He may return more tired 
than when he set out. The exhilaration of horseback rid- 
ing may prove far better, though perhaps involving much 
less muscular exertion. 

Nervous Tissue least affected by Starvation. — It is 

worthy of note that in fasting the nervous tissue is less 
reduced than any other tissue, being scarcely diminished 
by complete starvation. 

Blood Supply of the Brain. — Blood is supplied to the 
brain through four arteries : the right and left interna] 



248 PHYSIOLOGY. 

carotid arteries, and the right and left vertebral arteries. 
These arteries are so connected by cross-branches that 
if any three of them should be compressed, or the blood 
flow in them otherwise stopped, the fourth would still be 
able to give the brain blood enough for its work. When 
the brain is more active it receives a larger supply of 
blood. During sleep it is paler. 

Fainting. — If the supply of blood to the brain is shut 
off, unconsciousness quickly follows. In the ordinary 
faint the blood supply has been reduced, owing to the 
diminution of the blood pressure or heart's force. It may 
be due to inhibition of the heart from some emotion, or 
bad odor, as in a close room ; severe pain may be the 
cause ; a blow over the pit of the stomach may stop the 
heart by reflex action. Fresh air should be supplied, 
and the body laid flat on the .back. This position makes 
it easier for the blood to reach the brain and restore 
consciousness. Smelling salts (or ammonia) may stimu- 
late respiration and circulation. Sprinkling a little cold 
water on the face may have the same effect, but it is 
not necessary to pour a large quantity of water over the 
person. Rubbing the limbs toward the heart promotes 
the flow of blood, and tends to start the heart to activity. 

Apoplexy. — Apoplexy is caused by rupture of a blood 
tube and the formation of a clot that presses on the brain. 

Meningitis. — Meningitis is an inflammation of the 
membranes immediately surrounding the brain or spinal 
cord or both. 

The Water Cushion of the Brain. — Between the coats 
surrounding the brain and spinal cord there is a layer of 
liquid, comparable to that around the heart or lungs. 
When an undue amount of blood is sent to the brain, 



THE BRAIN. 249 

it is supposed that part of the cerebrospinal fluid is 
pressed out into the spinal cavity, thus relieving the pres- 
sure in the brain cavity. 

Relative Activity of Gray and White Matter. — The 

gray matter is, physiologically, more active than the white, 
and in keeping with this is the fact that the capillary 
network is closer in the gray matter than in the white. 
This is true of the spinal cord as well as of the brain. 

Reading. — Brain-work and Over-work, Wood ; The 
Brain and its Functions, Luys. 



Summary. — 1. The outside of the brain consists of gray matter, 
the inside of white matter. 

2. The twelve pairs of cranial nerves are distributed to the head, 
with the exception of the tenth and part of the eleventh. 

3. The cranial nerves include all the special senses but that of 
touch. 

4. Each hemisphere of the brain is connected with, and has chief 
control of, the opposite half of the body. 

5. The gray matter of the cerebrum is the seat of the will, sensation, 
thought, and emotion. 

6. The cerebellum regulates voluntary motion. 

7. Many of the cerebral functions have been located. 

8. The brain needs rest. In sleep less blood flows through the 
brain. 

9. Work reduces the size of nerve cells. During rest they increase 
again. 

Questions. — 1. Is there any special reason why the "speech cen- 
ter " should be in the left cerebral hemisphere ? 

2. Why does a light lunch sometimes enable one to go to sleep 
after mental work ? 

3. Why is it uncomfortable to hold the head down ? 

4. How does the nervous system resemble a telegraph system ? In 
what respects are the two unlike ? 

5. Name some remedies for sleeplessness. 



CHAPTER XVI. 

EFFECTS OF ALCOHOL ON THE NERVOUS SYSTEM. 

" Oh, that man should put an enemy into his mouth to steal away his brains !" 

The Effects of Alcohol on Nervous Tissue. — The physi- 
ological effects of alcohol which have been considered in 
connection with the muscles, circulation, digestion, etc., are 
quite subsidiary to its effects on the central nervous system. 

It is difficult to understand the extreme delicacy of 
organization of the nervous system. We can readily see 
how thoroughly nature has guarded this tissue by placing 
it in the most protected places in the body. But even 
after we have considered this point, we are not yet ready 
to comprehend the fine texture and sensitiveness of this 
tissue above all others. It is this high degree of suscep- 
tibility of the nervous system that renders it peculiarly 
subject to the effects of alcohol. The injury done to the 
brain by alcohol may not be readily discernible ; but as it 
is so delicate we cannot expect to trace the changes in 
structure as we might in some of the coarser organs of 
the body. For instance, the rupture of a small blood-tube 
in most of the tissues of the body results in a small clot, 
which ordinarily is a matter of no special consequence ; it 
forms a " black-and-blue spot," which is hardly more than 
a temporary inconvenience, for it does not ordinarily inter- 
fere with the function of the organ. It is soon absorbed, 
and all traces of it pass away. Not so with the brain : a 
clot produces pressure on the delicate nervous tissue, which 
results in paralysis — more or less complete — or death. 

250 



EFFECTS OF ALCOHOL ON NERVOUS SYSTEM. 2$ \ 

Effects of Small Doses of Alcohol on Mental Opera- 
tions. — The common, but erroneous, idea is that alcohol 
stimulates the brain to a higher degree of activity. There 
does appear to be an exhilaration for a short time, but this 
is undoubtedly due to the increased flow of blood to the 
brain ; for the liquor has paralyzed the smaller blood- 
tubes, thus allowing the brain to be flushed with blood. 
But careful experiments show that any temporary increase 
in mental activity, following small doses of alcohol, is 
always at the expense of accuracy and power, and that 
its effects cannot truly be called stimulating. And this 
period of exhilaration is extremely short-lived. In de- 
scribing his methods of work, Helmholtz said that slight 
indulgence in alcohol instantly dispelled his best ideas. 
Professor Gaule states that once during the strain of an 
examination he suddenly stopped his wine and beer, and 
was surprised to find how much better he could work. 
An eminent professor in Leipsic once said that the Ger- 
man students could do twice as much work if they would 
let their beer alone. Dr. August Smith has found that 
moderate, non-intoxicant, doses of alcohol lowered his 
ability to memorize as much as 70 per cent. 

Permanent Effects of the Continued Use of Alcohol. — 

" The long-continued use of quantities not immediately so 
disastrous, produces various structural changes, which are 
often markedly perceptible ; and in chronic alcoholic dis- 
ease, hardening of the brain structure, increase of the con- 
nective tissue, with diminution of the proper brain cells, 
thickening of the membranes, and effusions of serous fluid 
into the ventricles or cavities, are among the appearances 
often found. All these changes are usually accompanied 
with inflammatory and other degenerative processes, with 



252 PHYSIOLOGY. 

a lowering and perversion of function, and with premature 
decay of all the mental and physical powers." — Palmer. 

Dr. Clum in his work entitled Inebriety, its Causes, its 
Results, its Remedy, says : " The most important part of 
man is his nervous system ; the cerebrospinal, sympathetic, 
and vasomotor being intimately interwoven and connected, 
composing the whole. The great nervous center, the brain, 
with its hemispheres, its gray and white matter, is the 
most complex of all complexities. The nerve fibers not 
only connect every cell with every other cell, but unite all 
nervous structures into one, making the entire body a 
complete whole, and forming close and direct sympathy 
between the intellect and the physical organization. 

" The mind and body are so intimately connected that 
exhausting excess of either acts and reacts on the other. 
Excessive work, either intellectual or physical, the sudden 
loss of property, intense disappointment, great trouble, un- 
requited affections, etc., may impart a shock to the senses 
through the mind, which, extending to the molecules of 
the brain, disturbs their normal action ; and a sufferer 
thus worn and debilitated with the cares of life, with an 
enfeebled will power, the result of nervous exhaustion, 
experiences a craving for some form of stimulant to ' brace 
him up.' He is on the verge of inebriety, or of insanity, 
or both, and if he indulges in alcoholic beverages he 
becomes an inebriate. Any disease inherited or acquired, 
acting either directly or indirectly upon the nervous system, 
may act as the predisposing, exciting, or complicating and 
protracting cause of alcoholic inebriety." 

" Inebriety is often, too often, observed to flourish in 
the richest and most promising soil. The clergyman, the 
lawyer, the editor, the student, and all others who use 
their intellectual faculties to excess, as well as -the mechanic, 



EFFECTS OF ALCOHOL ON NERVOUS SYSTEM. 253 

the laborer, and those who excessively exert their physical 
system, have unnatural longings for something to restore 
the exhausted energies of mind and body. 

" The excessive worry of one man, the exhausting ex- 
cesses of another, and the overwork of others, lead to 
organic lesions and nervous defects, and the disease 
inebriety, an ungovernable craving for alcoholic drinks, is 
the result." 

Dr. Crothers, author of Diseases of Inebriety, says, " I 
have often been made impatient in listening to the lecturer 
presenting the ' scientific aspects of the alcohol question ' 
to an audience, to see him illustrate extensively with 
charts, and spend hours to show the effects of alcohol 
upon the coats of the stomach, and upon the structure of 
the liver and the kidneys, and never allude once to the 
brain; when the fact is, alcohol's principal effect is upon 
this organ, and the functions of this organ so far transcend 
the functions of all the others, that I might say, there is 
no comparison." 

MORAL DETERIORATION PRODUCED BY ALCOHOL. 

[Professor H. Newell Martin.] 

" One result of a single dose of alcohol is that the con- 
trol of the will over the actions and emotions is temporarily 
enfeebled ; the slightly tipsy man laughs and talks loudly, 
says and dees rash things, is enraged or delighted without 
due cause. If the amount of alcohol be increased, further 
diminution of will power is indicated by loss of control 
over the muscles. Excessive habitual use of alcohol 
results in permanent overexcitement of the emotional 
nature, and enfeeblement of the will ; the man's highly 
emotional state exposes him to special temptations, to 



254 PHYSIOLOGY. 

excesses of all kinds, and his weakened will decreases the 
power of resistance ; the final outcome is a degraded 
moral condition. He who was prompt in the performance 
of duty begins to shirk that which is irksome, energy gives 
place to indifference, truthfulness to lying, integrity to 
dishonesty; for even with the best intentions in making 
promises or pledges there is no strength of will to keep 
them. In forfeiting the respect of others, respect for self 
is lost and character is overthrown. Meanwhile the pas- 
sion for drink grows absorbing ; no sacrifice is too costly 
which secures it. Swift and swifter is now the downward 
progress. A mere sot, the man becomes regardless of 
every duty, and even incapacitated for any which momen- 
tary shame may make him desire to perform. 

" For such a one there is but one hope, — confinement 
in an asylum, where, if not too late, the diseased craving 
for drink may be gradually overcome, the prostrated will 
regain its ascendency, and the man at last gain the victory 
over the brute." 

NARCOTICS. 

Definitions of Narcotics. — Gould's Dictionary of Medi- 
cine, one of the very best authorities, thus defines narcotic : 
"A drug that produces narcosis" and narcosis, as " the 
deadening of pain, or the production of incomplete or com- 
plete anesthesia by the use of narcotic agents, such as the 
use of anesthetics, opium, and other drugs." It is common, 
however, to treat of chloroform, ether, chloral hydrate, etc., 
in a group by themselves under the designation Anesthetics. 

The Century Dictionary thus defines narcotic : " A sub- 
stance which directly induces sleep, allaying sensibility and 
blunting the senses, and which, in large quantities, pro- 
duces narcotism or complete insensibility. Opium, Canna- 



EFFECTS OF ALCOHOL ON NERVOUS SYSTEM. 255 

bis Indica, hyoscyamus, stramonium, and belladonna are 
the chief narcotics, of which opium is the most typical. 
Direct narcotics . . . either produce some specific effect 
upon the cerebral gray matter, or have a very decided 
action on the blood supply of the brain." 

Some authorities class alcohol with the narcotics. 



OPIUM. 

Opium. — Opium is the dried and thickened juice of the 
head, or capsule, of a species of poppy. Incisions are 
made in the partially ripened heads ; the milky juice ex- 
udes ; after about twenty-four hours the partially dried 
and thickened material is scraped off with a dull knife. 
Most of the opium comes to this country from Smyrna, 
with a smaller quantity from Constantinople. As gathered 
it is a reddish brown, sticky substance of peculiar odor. 
It is soluble in water, alcohol, and dilute acids, to all of 
which it gives a deep brown color. It is a very complex 
substance, but the chief constituent is morphia, or mor- 
phine, to which the properties of opium are due. One 
fourth of a grain of morphine is equal to a grain of opium 
of the average strength. " Opium was known to the 
Greeks, but was not much used before the seventeenth 
century ; at present it is the most important of all medi- 
cines, and its applications the most multifarious, the chief 
of them being for the relief of pain and the production of 
sleep. Its habitual use is disastrous and difficult to break 
up. It is classed as a stimulant narcotic, acting almost 
exclusively on the central nervous system when taken in- 
ternally ; in large quantities it is a powerful narcotic poison, 
resulting in a coma characterized by great contraction of 
the pupils, insensibility, and death." — Century Dictionary. 



256 PHYSIOLOGY. 

Properties and Uses of Opium. — The United States 
Dispensatory makes the following statements as to its 
medical properties and uses : " Opium is a stimulant nar- 
cotic. Taken by a healthy person in a moderate dose, it 
increases the force, fullness, and frequency of the pulse, 
augments the temperature of the skin, invigorates the 
muscular system, quickens the senses, animates the spirits, 
and gives new energy to the intellectual faculties. Its op- 
eration, while thus extending to all parts of the system, is 
directed with peculiar force to the brain, the functions of 
which it excites sometimes even to intoxication or delirium. 
In a short time this excitation subsides; a calmness of the 
corporeal actions, and a delightful placidity of mind suc- 
ceed ; and the individual, insensible to painful impressions, 
forgetting all sources of care and anxiety, submits himself 
to a current of undefined and unconnected but pleasing 
fancies, and is conscious of no other feeling than that of a 
quiet and vague enjoyment. At the end of half an hour 
or an hour from the administration of the narcotic, all con- 
sciousness is lost in sleep. The soporific effect, after hav- 
ing continued for eight or ten hours, goes off, and is often 
succeeded by more or less nausea, headache, tremors, and 
other symptoms of diminished or irregular nervous action, 
which soon yield to the recuperative energies of the sys- 
tem, and, unless the dose is frequently repeated, and the 
powers of nature worn out by overexcitement, no injurious 
consequences ultimately result. Such is the obvious oper- 
ation of opium when moderately taken ; but other effects, 
very important in a remedial point of view, are also ex- 
perienced. All the secretions, with the exception of that 
from the skin, are in general either suspended or dimin- 
ished ; the peristaltic motion of the bowels is lessened ; 
pain and inordinate muscular contraction, if present, are 



EFFECTS OF ALCOHOL ON NERVOUS SYSTEM. 2$ J 

allayed ; and general nervous irritation is composed, if not 
entirely relieved." 

Cocaine. — Cocaine is an alkaloid extract of a shrub 
native to the Andes. It is much used by the natives for 
sustenance during long journeys. It is a cerebral stimu- 
lant, developing a remarkable power of enduring hunger 
and fatigue. lis effects are similar to those of coffee, but 
are more intense. Large doses have a narcotic effect and 
cause hallucinations. Its long-continued use is followed 
by insomnia, decay of moral and intellectual power, ema- 
ciation, and death. Locally, it is a powerful anesthetic in 
a limited area of surface, hence is valuable for minor sur- 
gical operations. 

Chloral Hydrate. — This drug is frequently, but incor 
rectly, called chloral. It is a powerful hypnotic, anti- 
spasmodic, and depressant to the brain and spinal nerve 
centers, and, to a limited extent, is an anesthetic. It is 
very useful in fevers accompanied by cerebral excitement, 
and in convulsions. Its hypnotic effects have led to its 
use by individuals without a physician's prescription, and 
often with fatal results. No drugs of this class should be 
used except under the advice of a physician. 

Chloroform. — In a similar way this anesthetic, whose 
discovery is one of the greatest importance in modern sur- 
gery, is abused for the sake of its effect on the system, 
and the hold such a habit gets over the user is similar to 
that of the alcohol or opium habit. 

The Use of Narcotics. — The use of anesthetics and 
narcotics may all be said to be typified by the use of alco- 
hol. Not that they are all stimulants, though many of 
them are, in small doses, or in the earlier stages of their 



258 PHYSIOLOGY 

effects. They all act on the nervous system. They pro- 
duce a pleasurable effect or they bring relief from pain. 
The use of many of them is begun during illness, when 
they are administered to relieve pain, as in neuralgia. 
The habit, once formed, is hard to break. Others, having 
heard of the soothing effects of these drugs, are unwise 
enough to experiment on themselves. Only the confes- 
sions of such victims, and the degrading effects on char- 
acter, show how powerful is the sway which this class of 
drugs gains over those who yield to their influence. Let 
no one flatter himself that he has a strong will and can 
control himself. The history of their use is ever the 
same. They enslave. They destroy. 

Tobacco. — The use of tobacco is needless. Man gets 
along well enough without it. It is injurious to many. It 
is an expensive habit. Many a man spends enough on 
tobacco to send a boy through college. With the excellent 
cheap printing of to-day, many of the very best books may 
be bought for the money that is paid for as many cigars. 
Even for those who can abundantly afford it, it seems ex- 
tremely selfish, when it is needless, and there is so much 
good that might be done with the money. Another very 
selfish feature is that so many men do not seem to con- 
sider the fact that the air is public property, and they 
have no right to fill the air with any gas or smoke that is 
offensive to others. Very likely many men derive great 
comfort from the use of tobacco after they have once 
formed the habit, but most of these were made sick in 
learning, showing that the use is unnatural. 

Nicotine. — The active material in tobacco is a sub- 
stance called nicotine. It is a violent poison. A drop of 
it in concentrated form will kill a dog. 



EFFECTS OF ALCOHOL ON NERVOUS SYSTEM. 259 

General Effects of Tobacco on the System. — Tobacco 
usually diminishes the natural appetite for food and inter- 
feres with digestion. It often affects the stomach and 
induces a craving for alcoholic drink. The eyes are fre- 
quently affected. Smoking often irritates the mouth and 
throat sufficiently to make the voice husky. The heart 
also is very frequently affected, the beat becoming un- 
steady. The muscles are in some cases weakened and 
affected by trembling. 

Cigarette Smoking. — It seems to be clearly proved 
that cigarette smoking is very injurious, especially to boys. 
And if men smoke cigars, the example is set for the boys 
to smoke cigarettes. Some of the cigarettes are said to 
be steeped in preparations of opium, so that the use of 
cigarettes is often subjecting the user, not only to the 
tyranny of tobacco, but that of opium as well. 

Perhaps Robinson Crusoe might have been excused for 
using tobacco, having no one to save money for, no unfor- 
tunates to aid, no children to educate, no one to whom he 
might set a bad example, no one whose breath of air he 
could contaminate, no one to smell his breath, no one to 
see the offensive results. But a man, living in the society 
of so many to whom this habit, in all its features, is so 
disgusting and in every way offensive, ought seriously to 
consider whether he is doing right in continuing such a 
practice. 

Many boys seem to think it is manly ; they wish to do 
as others do. It is not manly to imitate any one. Do 
nothing simply because some one else does it. To do this 
is to be a slave, to be led. And one bad feature of the 
tobacco habit is that one makes himself a slave to the 
weed. For, like other narcotics, it has a powerful in- 



260 PHYSIOLOGY. 

fluence on the system, and the habit, once formed, is hard 
to break. 

How many men have been heard to say, " I wish I had 
never formed the habit." 

Has any one in middle or later life ever been heard to 
say, " I wish I had formed this habit" ? 

Reading. — The Nature and Effects of Alcohol and Nar- 
cotics, Luce ; Diseases of Inebriety, Cr others ; Inebriety, its 
Causes, its Results, its Remedy, Clum ; Inebriety, Palmer. 



Summary. — i. The most important physiological effects of alcohol 
are on the nervous system. 

2. Many physicians regard inebriety as a disease. 

3. The use of alcohol weakens the will power. 

4. Narcotics produce anesthesia, or loss of feeling. 

5. Hence narcotics are useful in deadening pain, but their use is 
dangerous. 

6. Opium is one of the most widely used of the narcotics. 

7. Tobacco is needless and in many cases harmful. 

8. Cigarette smoking is very injurious, especially to the young. 

Questions. — 1 . Why is cigarette smoking more injurious than 
cigar smoking ? 

2. How does the opium habit often begin ? 



CHAPTER XVII. 

GENERAL CONSIDERATIONS CONCERNING THE NERVOUS 

SYSTEM. 

Nerve Stimuli. — Natural nerve impulses that run out- 
ward are ordinarily started by the action of some nerve 
cell or cells, as from the gray matter of the brain or of 
the spinal cord. 

Nerve impulses coming inward may be started in sev- 
eral ways. Ordinarily by some one of a few forces that 
are capable of affecting the nerve endings. Mechanical 
force, as pressure, acts on the nerve endings of the skin, 
and starts nerve impulses which are carried to the brain 
and rouse certain cells to activity, and give us the sensa- 
tion of touch. The vibrations known as light excite the 
special nerve endings in the retina, but affect no other 
nerve endings. Sound is appreciated only by the endings 
of the auditory nerve. Certain gases or fine particles 
affect the olfactory nerve endings, and certain substances 
may give the sense of taste by acting on the ends of nerves 
in the mouth. Different nerves, then, are adapted to re- 
ceiving impressions from the action of different forces. 

Kinds of Nerve Stimuli. — There are four kinds of 
nerve stimuli, — electrical, mechanical, thermal, and chemi- 
cal. In experiment, electricity is usually the best stimulus ; 
mechanical stimuli, as used in the experiments with the 
muscle-nerve preparation from the frog, by cutting or 
pinching the nerve, may be employed ; heat, as in touch- 

261 



262 PHYSIOLOGY. 

ing the nerve with a hot wire, or holding a hot wire near 
the nerve, may be used as a stimulus ; chemical stimuli, as 
acids, strong salt solution, etc., may also be used. 

Essential Similarity of All Nerve Fibers. — It is to be 

noted that while special stimuli act on specially modified 
nerve endings, all nerve fibers are essentially alike, and 
the nerve impulse, however started, is probably the same 
kind of force. For instance, cutting the optic nerve, or 
severe shock, as a blow on the head, causes a sensation of 
light not quite so definite, but essentially the same as 
though light had acted on the retina, and thus started the 
nerve impulse, instead of a mechanical stimulus acting on 
the nerve fibers between the retina and the brain. 

Relation of Stimulus and Sensation. — If we apply a 

stimulus of a given intensity, as of an electric current, 
whose intensity can be measured, it causes a sensation of 
a certain degree. Doubling the stimulus, or increasing it 
by a definite amount, does not increase the intensity of the 
sensation to the same degree. The sensations do not 
increase at the same rate as the stimuli. To increase the 
sensations arithmetically, the stimuli must increase geo- 
metrically. 

Reaction Time. — " Reaction time " is the time between 
the application of a stimulus and the signal given as a 
response to show that the stimulus has been "felt." Thus 
a blindfolded person gives a signal as soon as he is touched. 
This interval between the stimulus and response varies 
with the individual, mode of stimulation, health, attention, 
etc. It is from one tenth to one fifth of a second ; is short- 
est for touch ; longer for sight than for hearing. The total 
reaction time is occupied by (i) the time of conducting 
the nerve impulse to the brain, (2) the time occupied in 



NERVOUS SYSTEM IN GENERAL. 263 

the cerebral cortex in the perception of the sensation 
and the formation of the volition, (3) the time of conduct- 
ing the motor impulse and giving the signal. The greater 
part is in the middle interval, i.e. the central elaboration, 
during which the entering impression gives rise to an out- 
going impulse. 

Reflex Action. — In a previous diagram of reflex action, 
a single cell was represented as receiving the afferent im- 

Nerve Cells connected by Interlacing Nerve Network 




Afferent Nerve Fiber // YV Efferent Nerve Fiber 



Sensory s&ryh lld|Muscl« 

Epitheliur 



Fig. 83. Diagram of Reflex Action. 

pulse and sending out an efferent one. It is more proba- 
ble that at least two cells are concerned in such an act, one 
receiving the incoming impulse, and influencing, by means 
of fine connecting branches, a second cell which sends out 
the motor impulse, as shown in Fig. 83. 

Connection of Brain Centers. — We have seen that the 
brain functions are more or less localized. We also know 
that the cortex receives impressions through the channels 



264 



PHYSIOLOGY, 



Writing 



of the different sense organs, and we can respond through 
various channels, — speech, writing, facial expression, etc. 
We would therefore expect, theoretically, that the various 
parts of the cortex of the brain are connected. As a 

matter of fact, we 
find anatomically 
that this is the 
case. Not only 
are the cells of 

Speech the gray mat _ 

ter connected 
with the various 
parts of the body, 
but cells of differ- 
ent parts of the 
cortex are in com- 
munication with 
each other by what 
are called " as- 
sociation fibers." 
Thus a sensation 
roused in one part 
of the brain gives 
rise to the sending 
out of an impulse 
from another part 

Fig 84. Connection of Brain Centers by Association > L 

Fibers. (After Landois and Stirling.) of the brain to 

(The dotted lines from the hand, mouth, and eye rep- produce the re- 

resent afferent fibers from the skin, muscles, and joints 
of the hand, lips, orbit, etc.) Sponse. 




The Nature of Sensation. — Of the real nature of sen- 
sation we know but little. Like consciousness, we call it 
a condition of the gray matter of the cerebral convolutions. 



NERVOUS SYSTEM IN GENERAL. 26$ 

An external stimulus acts on the nerve endings, and starts 
a nerve impulse. This impulse passes along afferent nerve 
fibers, and excites certain cells of the gray matter of the 
cerebrum, thus producing a sensation. Sensation is the 
consciousness of stimulation. 

Subjective Sensations. — But sensations may be subjec- 
tive ; that is, they may exist without any corresponding 
external exciting cause. For some unexplained reason the 
cells of the brain are active, and their activity, however 
caused, constitutes what we call a sensation. Certain 
drugs, such as hashish, may excite an unusual degree of 
cerebral activity. Here the action is roused through af- 
ferent nerves, but through unusual channels ; that is, the 
subject sees, but not through the nerves of sight. Many 
hallucinations are explainable to a certain degree ; others 
we cannot account for. 

The Relative Nature of Sensations. — If one hand be 
held in a basin of hot water and the other in a basin of 
cold water, and then the two be suddenly plunged into 
a third basin containing tepid water, a sensation of cold will 
be received from the hand that was in the hot water, while 
the hand from the cold water will feel heat. Sensations 
depend on comparison and contrast. After listening to 
low sounds, a sudden loud noise is painful ; and after hear- 
ing loud noises, it is difficult to detect slight sounds. We 
hardly notice the gradual fading of the light at sunset. 
And the nose does not usually detect the slow fouling of 
the air in a room ; but let one come in from the fresh out- 
side air, and the contrast is striking. A constant current 
of electricity usually causes a muscular shortening at the 
time the current enters the muscle and at the time when 
the current is stopped, that is, at the " making " and the 



266 PHYSIOLOGY. 

" breaking " of the current ; but the muscle ordinarily re« 
mains inactive while the current is passing. 

Induction Current used in Physiological Experiment. — The in- 
terrupted current, or induction current, is therefore commonly employed 
as a stimulus in physiological experiment. A sudden change seems 
to be requisite for producing the nerve impulse necessary to rouse 
a sensation in ordinary circumstances. Pressure may be applied so 
gradually that we fail to notice it. The art of the pickpocket, of the 
ventriloquist, of the sleight-of-hand performer, depends largely on this 
fact. Attention is called to something else, and the work is either 
quickly done when attention is completely absorbed on something else, 
or the act is so gradual that no sudden change is noted. In smelling 
it is often necessary to sniff; the sudden rush of particles of air bearing 
the odorous particles against the surface bearing the nerve endings 
seems to be necessary. 

Dreams. — Dreams, due to more or less perfect brain activity, are 
often traceable to nerve impulses brought from the digestive tract, from 
the respiratory organs, from the skin (heat and cold and pressure), 
from sound, from any internal organ, according to the condition of the 
blood, pressure, etc. It seems to be well settled that dreams seeming 
to cover long periods of time really take place in a very short space of 
time, just as sometimes during waking hours thoughts fly through the 
mind in countless numbers and with incredible swiftness. 

Ignoring Nerve Currents. — Do we have dreams when we recall 
none ? Without attempting to answer this question it is well to note 
that the brain undoubtedly is constantly receiving nerve currents to 
which it pays no heed, or at least of which we are not conscious. 
For instance, our clothing is touching nearly the whole of the surface 
of our bodies, and, plainly, the surfaces thus touched are affected. 
Undoubtedly currents go to the brain, but as they are of no significance 
in ordinary circumstances, we learn to disregard them. If a savage 
were suddenly clothed as fully as we are, he would, for a long time, 
be continually conscious of the fact. 

Judgment. — In what is called Aristotle's experiment, 
the experimenter crosses the first and second finger, and 
feels an object with the fingers thus crossed and eyes shut 



NERVOUS SYSTEM IN GENERAL. 267 

If a marble be rolled about by the two fingers thus crossed, 
it seems to be two. Here we use judgment with the sen- 
sation. Ordinarily, we could not feel, at the same time, 
one simple solid object with the outside of the first and the 
inside of the second finger. This illustrates how we are 
constantly using our judgment in interpreting our sen- 
sations. We see few things as they are in themselves. 
We see nearly everything in the light of past experiences. 

Lingering Effect of Sensations. — We have noted the lingering 
effects of sensations, how sights and sounds linger and are fused one 
with the other. So we get continuous light from a series of flashes 
if they follow each other in sufficiently rapid succession, and continu- 
ous sound from a series of sounds that would be heard separately if 
they are more than about a sixteenth of a second apart. So with 
touch, if the finger be held against the teeth of a revolving wheel, if 
the wheel revolve slowly, the touch of each tooth may be felt, but when 
it whirls more rapidly the sensation becomes that of continuous pres- 
sure. Experience and experiment both go to show that probably 
nothing is wholly forgotten. Whatever acts upon a cell of nervous 
matter makes its mark. It may become dim, but it is never completely 
obliterated. The testimony of persons rescued from drowning, and other 
similar experiences, goes to show that the record was yet in the mind. 
We may fail to recollect, but we eVer remember. 

Habits are Acquired Reflex Actions. — The work of 
the spinal cord is that of a subordinate officer, whose duty 
is to relieve his superior, the brain, of many small tasks, 
and to afford him relief from having all the details con- 
stantly on his mind. If we learn to do many things me- 
chanically, we save the effort of doing them by conscious 
effort and act of will. Whatever we do for the first time 
requires careful attention. To learn any new muscular 
action, such as a new step in marching, fingering a musical 
instrument, or typewriting, requires effort; they produce 
more or less fatigue. Subsequent effort in doing the same 



268 PHYSIOLOGY. 

thing is very much less, showing that, in many cases, 
fatigue is mental rather than muscular. What we do from 
habit, and cheerfully, is easily done. Hence the desira- 
bility of forming good habits, that we may, without un- 
necessary effort, — that is, without loss of energy, — do 
what is needed for our well-being. 

Fatigue from Standing. — We are not conscious of 
expending energy in standing until we begin to be weary ; 
but the fact that a blow on the head causes one to fall 
reveals the fact that the brain is constantly sending mes- 
sages to the muscles to make them act. The shock of the 
blow has stopped the sending forth of these messages, and 
so the body is no longer supported. None of the muscles 
that support the body have been injured or even touched. 

The Usefulness of Resting. — We have, in youth, such 
a boundless store of energy that we do not sufficiently 
consider these matters. But if one wishes to follow the 
intellectual life long and successfully, he must learn to 
economize energy, and to direct his forces into useful 
channels. And one important part of this knowledge is 
learning how to rest. It is an art that very few have well 
learned. 

Nervous System compared to a Telegraph System. — 

The brain is like a telegraph office in both receiving and 
sending out messages. Unlike the telegraph office, it has 
one set of fibers to bring currents in (afferent), and another 
to carry currents outward (efferent). 

Efferent Currents. — We have concerned ourselves thus 
far chiefly with efferent nerve fibers and efferent currents. 
These efferent currents are sent mainly to muscles, to 
make them shorten or to relax, or to gland cells, to control 



NERVOUS SYSTEM IN GENERAL. 269 

their activity. The only other efferent currents, so far 
as known, are those which possibly go to the cells of 
the tissues to regulate their nutrition or their heat pro- 
duction. 

Having given so much attention to the outgo of nerve 
impulses, let us ask the question, " What about the in- 
coming nerve currents ? " 

Afferent Currents. — " All life long the never-ceasing 
changes of the external world continually break as waves 
on the peripheral endings of the afferent nerves ; all life 
long nervous impulses, now more, now fewer, are continu- 
ally sweeping inward toward the center ; and the nervous 
metabolism, which is the basis of nervous action, must be 
at least as largely dependent on these influences from 
without as on the mere chemical supply furnished by the 
blood. We must regard the supereminent activity of the 
cortex and the characters of the processes taking place in 
it as due not so much to the intrinsic chemical nature of 
the nervous substance, which is built up into the cortical 
gray matter, as to the fact that impulses are continually 
streaming into it from all parts of the body ; that almost 
all influences brought to bear on the body make themselves 
felt by it. To put the matter in a bald way we may ask 
the question, What would happen in the cortex if, its or- 
dinary nutritive supply remaining as before, it were cut 
adrift from afferent impulses of all kinds ? We can hardly 
doubt but that volitional and other psychical processes 
would soon come to a standstill, and consciousness vanish. 
This is, indeed, roughly indicated by the remarkable case 
of a patient whose almost only communication with the 
external world was by means of one eye, he being blind in 
the other eye, deaf of both ears, and suffering from gen- 



270 PHYSIOLOGY. 

eral anesthesia. Whenever the sound eye was closed he 
went to sleep." — Foster. 

Let us turn from the consideration of outgoing, or 
efferent, nerve impulses and their resulting action to tne 
incoming, or afferent, nerve impulses and the activity 
which they rouse in the gray matter of the cerebrum — 
sensation. 

Reading. — Wear and Tear, Mitchell ; Power through 
Repose, Call ; Technique of Rest, Brackett. 



Summary. — i . Nerves may be stimulated by mechanical force, 
chemical action, heat, and electricity. 

2. Electricity is the most convenient nerve stimulus for physiological 
experiment. The induction current is usually employed. 

3. To increase sensations arithmetically stimuli must increase geo. 
metrically. 

4. Reaction time is the interval between the application of a stimu- 
lus and the response. 

5. Sensations are relative. 

6. Habits are acquired reflex actions. 

7. The nervous system is unlike the telegraph system in using one 
set of fibers for receiving and another for sending messages. 

Questions. — 1. Is the difference in "reaction time" in individuals 
of any significance ? 

2. Why are slight wounds in a battle often unperceived ? 



CHAPTER XVIII. 
THE GENERAL SENSES. 

The Body a Collection of Organs. — We have been 
considering the body as a collection of organs working 
together to serve the brain, the mechanism through which 
the mind operates. 

We have especially studied the muscles as the only 
means by which the mind manifests itself to the outer 
world. 

Influences from the External World. — But how much 
mind would we have if we did not receive something from 
the outer world ? Read the story of Kaspar Hauser. We 
are continually getting knowledge of the outer world and 
of the condition of our own bodies through the afferent 
nerves. We may never know fully what consciousness and 
thought are, but we can understand that to the brain are 
continually streaming nerve impulses that convey messages 
which the brain more or less completely interprets. 

Classification of the Senses. — These incoming currents 
pass along myriads of nerve fibers. But the nerve fibers 
are all essentially alike. And the kinds of sensations that 
these currents arouse in the brain are but few. It is diffi- 
cult to classify the senses, but it will serve our convenience 
to divide them into two groups. 

General Sensations and Special Senses. — In distinc- 
tion from the special senses, sight, hearing, etc., are the 

271 



272 PHYSIOLOGY. 

general sensations such as muscular sense, pain, hunger, 
thirst, fatigue, nausea, satiety, faintness, etc. They are 
often called "common sensations," and Martin designates 
them as " sensations which we do not mentally attribute to 
the properties of external objects, but to the conditions of 
our own bodies." 

General Sensations. — Nerve endings in different parts 
of the body may be affected by the blood and the lymph, 
and give us sensations of comfort, discomfort, restlessness, 
fatigue, faintness, etc. These are called general sensa- 
tions. They are probably due to the condition of the 
blood, or to the condition of nutrition of the various parts 
of the body. Thus after muscular exercise the muscles are 
acid in their reaction, while they are alkaline after resting ; 
after exercise carbon dioxid accumulates in them to a cer- 
tain extent. Hunger and thirst come on after abstinence 
from food and drink, or after work exhausting the tissues. 
The presence of the various waste products, or the condi- 
tion of the cells as the result of their activity, acting 
through the nerve endings in the tissues, keep the nerve 
centers informed as to the condition of the parts of the body. 
If these conditions are extreme, we may have definable sen- 
sations, but ordinarily the sensations are of an undefinable 
sort which we designate as "general sensations." 

The Muscular Sense. — As an example, we will take 
the case of estimating the weight of an object by holding 
it in the hand. Our estimate is thought by some to be the 
result of (i) direct consciousness of the degree of effort 
put forth ; but probably it is (2) a sensation, or complex of 
sensations, aroused by nerve impulses from the organs 
used. There are afferent nerve fibers with endings in 
(1) the skin, (2) the muscles and tendons, (3) the joints. 



THE GENERAL SENSES, 273 

In extending the arm and moving it up and down, all three 
of these sets of nerve endings are probably stimulated, and 
impulses thence conveyed to the brain. 

Muscular Sense and General Sensibility. — It is a 

matter of doubt whether or not the impulses from the 
muscles are predominant, and consequently whether the 
term " muscular sense " is the most appropriate. Peculiar 
nerve endings have been found in the tendons, and the 
joints are believed to have an especially rich nerve supply. 
It is not necessary that we actively use the muscles to have 
sensations of this kind. In passive moments, as the rais- 
ing of the arm by another person, we have a "sense of 
position" of the parts, a considerable share of which is 
probably due to the tension of the skin and changes in the 
joints. There is, of course, some tension of the muscle, 
even in this passive movement, that might affect nerve 
endings in it. The muscular sense is closely related to the 
general sensibility already mentioned, if not a modified 
form of it. 

Importance of Muscular Sense. — It is difficult to real- 
ize the importance of this sense in our daily experience. 
We probably underestimate it, and attribute to sight too 
much of our knowledge of the external world. The funda- 
mental facts concerning the objects about us are not ob- 
tained through sight alone. Such knowledge is based on 
complex judgments concerning the meaning of auditory 
and visual phenomena, according as they have, in past ex- 
perience, been interpreted by tactile and muscular percep- 
tions. That is, when reduced to its simplest terms our 
most practical and important knowledge of the world is 
the outgrowth of tactile and muscular perceptions ; by and 



274 PHYSIOLOGY. 

with them all other sense perceptions have been corrected 
and compared. 

Dependence of Sight on Muscular Sense and Touch. — 

An illustration of the assistance which touch and the mus- 
cular sense give to the sense of sight is furnished in the 
case of a boy who had been blind from birth, and received 
sight at the age of twelve years by means of a surgical 
operation. At first he could not distinguish a globe from 
a circular card of the same color until he had touched them. 
He knew the peculiar features of the dog and the cat by 
feeling, but not by sight. Happening one day to pick up 
the cat he recognized for the first time the connection be- 
tween the new sense of sight and the old familiar ones of 
touch and the muscular sense. On putting the cat down 
he said, " So, puss, I shall know you next time." 

Pain. — When a heavy weight is laid on the hand it ma)/ 
cause pain. It would at first seem that the ordinary pres- 
sure sense, when unduly exaggerated, becomes pain. But 
there seem good reasons for considering pain as a distinct 
sense from that of touch intensified. It is thought that 
there are, throughout all parts of the body, nerves of "com- 
mon sensibility " or " general sensibility," which keep the 
nerve centers informed as to the condition of all the various 
tissues, and that ordinarily we have no sensation resulting 
from the impulses ; to use the language of the psycholo- 
gist, " they do not rise above the threshold of conscious- 
ness." They may have some influence in adjusting the 
action of the different parts. We have seen how the blood- 
flow to any part is continually adjusted without our know- 
ing anything about it. But we are usually more or less 
conscious of the general condition of the body. We call 
by the name of " common sensations " such feelings as 



THE GENERAL SENSES. 275 

hunger, thirst, nausea, fatigue, depression, melancholy, 
restlessness, such as many experience preceding a thun- 
derstorm, the feeling of general discomfort known as 
malaise, and its opposite, the feeling of general well being. 
The body seems to have a set of nerves to give information 
as to the state of nutrition of the body, and as to its condi^ 
tion generally. These nerves, when the system is dis- 
ordered in any part, may bring messages that cause intense 
pain. Of course, they are warnings (they are more than 
mere warnings ; probably if the earlier indications of simple 
discomfort had been heeded the later more emphatic mes- 
sages of pain would not have been necessary). These mes- 
sages of pain demand attention. 

The Extent of Pain. — In reference to pain in the skin, 
it is held that the skin, too, has its nerves of general sensi- 
bility, and that these are distinct from those of touch and 
temperature sense. That when they are unduly stimulated 
they give rise to painful sensations. It is to be noted that 
the internal organs are ordinarily devoid of feeling, and 
that the skin is especially sensitive. The skin senses stand 
guard at the outposts, so to speak, of the body's camp, and 
give warning of approaching danger. No enemy may 
enter without being discovered by these keen sentinels, 
and the alarm is given. If it is not heeded, great harm 
may follow. And it is a comfort to know that the more 
severe wounds do not cause pain in proportion to their 
extent. When a person says his " lungs are sore " the 
pain is usually in the muscles of the chest from coughing. 
While there may be acute pain from the lungs, as in pleu- 
risy, there is often deep-seated lung disease without pain 
from the lungs themselves. The muscles of the chest and 
back may be strained by lifting, and the soreness is erro« 



276 PHYSIOLOGY. 

neously attributed to the lungs or kidneys. Hence there 
is frequently a wholly needless apprehension of deep- 
seated disorder, whereas in reality there is merely a strain 
of superficial muscles. In amputating a limb the chief 
pain is in cutting through the skin. Some excellent 
authorities still hold the view that pain is merely the 
result of intensifying any of the simple sensations ; but it 
is generally held that it results from the excessive stimula- 
tion of the nerves of general sensibility ; as Foster puts it, 
" the constantly smouldering embers of common sensibility 
may be at any moment fanned into the flame of pain." 

Pain a General Sense. — In the real "special senses," 

— sight, hearing, smell, taste, touch, and temperature sense, 

— we refer the sensation to some external object, whereas 
general sensations are subjective, referred to our bodies. 
Ordinarily we do not localize the common sensations, and 
a further indication of the relationship of pain and general 
sensation is in the lack of complete localization of pain. 
Slight pain, especially in the skin, may be closely located, 
but severe pain tends to become indefinite and diffuse. 
So we may class both the muscular sense and pain with 
the "general" rather than with the "special " senses. 

Hunger and Thirst. — The cause of these sensations in 
a healthy body is plainly the need of food and water 
throughout the system generally. The sensation of thirst 
manifests itself in the throat, and the longing may be tem- 
porarily relieved by merely moistening the throat. So 
hunger may, for the time, be appeased by filling the stom- 
ach with indigestible material. But the sensation soon 
returns. The system has a crying need, and it is not to be 
put off by any such frauds. That these sensations are 
really demands made by the body as a whole may be 



THE GENERAL SENSES. 2JJ 

shown by the fact that they are permanently relieved by 
introducing food and water into the body (by the rectum, 
for instance), in which case the throat and stomach have 
nothing given them directly. Since, however, food and 
drink naturally enter by the throat and stomach, the 
mucous membrane ot these organs has become spokes- 
man of the body for its demands. 

Reading. — Pain, Corning. 



Summary. — I. Brain action depends, in the long run, upon im- 
pulses from without. If we had no impressions, we could have no 
expressions. 

2. General sensations are referred to our bodies and their condition ; 
special sensations are regarded as attributes of external objects. 

3. The "muscular sense 1 ' probably depends chiefly on impulses 
from the tendons and joints. 

4. The muscular sense is necessary for the full interpretation of 
sight. It enables us to judge of the degree of effort put forth or force 
resisted. 

5. Pain is a general sensation. It is a warning — the cry of a senti- 
nel that an enemy has passed the picket line. 

6. Hunger and thirst indicate the need of food and drink. They are 
local signals of a general want. 

Questions. — 1. If we had no sense of pain, what might result? 
2. If we pass by a meal time without eating, why does the sense of 
hunger disappear? 



CHAPTER XIX, 

THE SPECIAL SENSES — TOUCH AND TEMPERATURE 

SENSE. 

What we learn by touching Objects. — Let one person 
rest the hand flat on the- table, palm upward, and close the 
eyes. An object placed on the palm, by another person, 
may give rise to various sensations, so that it may be 
described as rough or smooth, light or heavy, hot or cold, 
wet or dry, etc. If the object is very heavy or very hot, it 
may cause pain. If now the thumb and fingers are raised 
and applied to the object, more definite information will be 
gained as to its shape, size, surface, etc. Now raise the 
object in the hand, and further appreciation will be gained 
as to its weight. 

These experiments show that several sensations are in- 
volved in the handling of objects, and that the knowledge 
so gained is complex. 

Cutaneous Sensations. — The sensations from the ob- 
jects resting on the skin of the passive hand may, proba- 
bly, all be referred to impressions made on nerve endings 
in the skin, and are called cutaneous sensations. They 
include: (i) the pressure sense, or touch proper, (2) the 
temperature sense, and (3) pain. 

Nerve Endings in the Skin. — The skin consists of 
two layers, the epidermis and the dermis. We need now 
to recall those conical elevations of the dermis that we call 

278 







THE SENSE OF TOUCH. 279 

papillae. In these papillae are certain important nerve 
endings. There are several kinds of nerve endings in the 
skin and underneath it that receive the impressions which, 
carried to the brain, give us sensations of touch (and allied 
sensations to be considered soon). Pressure on the skin 
affects these nerve endings, and 
starts impulses that pass along the >^r\, 

sensor fibers to some nerve center, /' :U 

probably in the spinal cord, spinal B I 

• »llilllilllBHr"' Nerve 

bulb, or brain. Fibers 

Touch Corpuscles. — These 
"touch corpuscles" are not re- 
garded as essential for producing 
the sensation of touch, but some 
nerve endings in the skin do seem / """ 

necessary ; for if a nerve fiber be 

J Fig. 85. Papilla of Skin with 

touched, not at the end, but some- Touch corpuscle. 

where along its course, we get, not 

a sensation of touch, but a sensation of pain. Except in 

the mouth and nose, we get little, if any, sense of touch 

from any organ but the skin. The lining of the digestive 

tube and the internal organs generally are devoid of this 

sense. 

The Sense of Touch. — Of the special senses the most 
general is that of touch. Seeing and hearing, taste and 
smell, belong to very limited parts of the outside of the 
body, but we have the power of feeling all over the surface 
of the body. 

Touch the most General of the Special Senses. — 

Not only is the sense of touch the most general in being 
distributed over the whole of the body, but it is the most 
widely distributed sense throughout the animal kingdom. 



28o PHYSIOLOGY. 

As we descend the animal scale we find many of the lower 
animals lacking some of the senses that we possess. In 
many of the simpler forms of animal life there is no evi- 
dence of a sense of hearing, and it is extremely likely that 
if they have taste and smell, these senses are in a very 
rudimentary state of development. But in all these forms 
it is believed that " feeling " exists. Contact of their exte- 
rior with foreign objects is so often immediately followed 
by action that little doubt remains about their having the 
sense of touch. Even ameba may have, in a rudimentary 
state, the power to distinguish light, to taste, and to hear. 
Still we have little or no evidence on these points, while 
we are pretty sure that it feels. 

The Pressure Sense. — The sense of touch, proper, is 
strictly a pressure sense. If we test the skin to find what 
regions are able to detect the least pressure, it is found 
that the forehead is most sensitive, and nearly equally so 
are the temples, back of the hand, and forearm. 

Ability to detect Differences of Pressure. — The 

abiHty to detect differences of pressure is tested by finding 
what is the least addition to a weight required to make it 
seem heavier. For instance, if a weight of 1 1 grains is 
just perceptibly heavier than one of 10 grains, it does not 
follow that i grain added to a weight of ioo grains will 
give any palpable increase. To ioo grains must be added 
10 grains before additional pressure is felt; that is, what- 
ever the weight, there must be the same ratio of increase 
to increase the sensation. This is part of the law, already 
stated, of the relation of stimulus and sensation. The law 
is true only in a general way and will not apply in extreme 
cases. It is stated that the forehead, the lips, and temples 
appreciate an increase of one fortieth to one thirtieth of the 



THE SENSE OF TOUCH. 28 1 

weight estimated, while the skin of the head, the fingers, 
and the forearm require an increase of one twentieth to 
one tenth for its perception. 

After-Pressure. — The lingering effect of pressure, or 
after-pressure, may be noticed after taking off a tight hat, 
skate strap, shoe, or glove. 

Local Sign. — ■" If a point of the skin is touched, certain 
tactile corpuscles are irritated ; these, in turn, set up im- 
pulses in sensory nerve fibers, and these impulses are car- 
ried by the fibers, first to the spinal cord, and then to the 
brain, where the fibers end in ganglionic masses in the 
gray matter of the cerebral cortex. There are thus pro- 
jected, as it were, on the cortex of the brain, tactile centers 
for the hind leg, fore leg, neck, eye, ear, trunk, etc. ; and 
it follows that each point of the skin has a corresponding 
point in the cerebral cortex. Thus for each stimulation of 
a point of the cerebral cortex there is a local sign, and so 
we localize tactile impressions." 

Accuracy in locating Touch Sensations. — The accu- 
racy varies, and is ordinarily keenest where the nerves are 
most numerous. Where the sense of locality seems to be 
improved by cultivation, this appears to be due to keener 
discrimination in the brain cells, and not to changes in the 
nerves or nerve endings. This is indicated in the fact that 
if the fingers of one hand become more discriminating by 
practice, it will be found that the fingers of the other hand, 
without special training, are also improved. 

Test by Compass Points. — The delicacy of localizing 
touch is usually tested in this way. The blunted points of 
a light pair of compasses are allowed to rest gently on the 
skin of various parts of the body. If the two points are 



282 PHYSIOLOGY. 

very close together, they will be felt as one pressure. That 
part which can best distinguish, as two points of touch, 
these blunt points, is considered the most sensitive. By 
this test the tip of the tongue is the most sensitive, being 
able to distinguish, as two separate points of contact, the 
tips of the compasses when only one twenty-fifth part of 
an inch apart. Following is the order of degrees of sen- 
sitiveness : tip of tongue, tips of fingers, lip, tip of nose, 
eyelid, cheek, forehead, knee, neck; while the middle of 
the back seems least sensitive, the two points not produc- 
ing two distinct sensations until they are more than two 
and a half inches apart. In general those parts which are 
most used, and those parts which are more freely movable, 
are most sensitive ; for instance, the knee is much more 
sensitive than the middle of the thigh or the middle of the 
leg, and the elbow than the middle of the arm or forearm. 
If the compass points, about half an inch apart, be passed 
from the palm to the tips of the fingers, it will at first seem 
one line gradually separating into two diverging ones, 
owing to the keener localizing power as the finger tips are 
approached. 

Reference of Sensation to the Region of Nerve End- 
ings. — If the " funny bone," or "crazy bone," be hit, i.e. 
if the ulnar nerve be bruised against the bone, sharp pain 
may be felt in the wrist and hand, and soreness of these 
parts may be felt for days, though they are not in the 
least injured, but only the nerve at the elbow. The cur- 
rents along this nerve rouse sensation that we have learned 
to localize at the endings of the nerve fibers. So, too, 
after amputation of a hand or foot, there may for years 
be sensations referred to the missing member, probably 
due to irritation of the nerves of the stump. There is, 



THE TEMPERATURE SEATSE. 283 

then, no certainty of getting rid of a corn by ampu- 
tating a toe. 

The Temperature Sense. — Many cases are on record 
in which, from accident or disease, the pressure sense was 
lost and the temperature sense retained, or vice versa. 
Such facts have led to the belief that the temperature 
sense is distinct from that of touch, and has its own nerve 
fibers and nerve endings. 

Two Sets of Nerve Fibers for Distinguishing Heat and 
Cold. — Since heat and cold are only differences in the 
degree of heat, we would expect both of these kinds of 
impressions to be received through one set of nerves. 
There seems, however, to be good evidence of two sets of 
nerve fibers, one for heat and the other for cold. In the com- 
mon experience of the foot "going to sleep" by pressure 
on the sciatic nerve, or the arm from compression of the 
brachial nerve, the skin may be found, at a certain stage, 
to be only slightly sensitive to warmth, while distinctly 
sensitive to cold. In some diseases of the spinal cord the 
skin may be affected by warmth, but not by cold. The 
sensations of cold and pressure seem to be usually lost 
or retained together, while those of warmth and pain 
have a similar connection. But more accurate results are 
obtained by touching the skin with a blunt metal pencil, 
warmed or cooled. 

Warm Spots and Cold Spots. — If this be applied at 
regular close intervals, it is found that some places feel the 
warm point, while others feel the cold. In this way the 
skin has been mapped out into "warm spots" (warmth- 
perceiving spots) and "cold spots" (cold-perceiving spots), 
and still other areas seem not sensitive to temperature. 



284 PHYSIOLOGY, 

Heat or cold, if applied directly to a nerve trunk, does not 
rouse sensations of temperature, but, if strong enough, 
produces pain. If the elbow be dipped into water at the 
freezing point, a sensation not of cold but of pain is caused, 
and is felt in the hand. Heat and cold are not felt in the 
digestive tube except at or near the openings. If very hot 
liquid be swallowed, it may cause pain in the gullet and 
stomach. If a considerable quantity of warm liquid be 
taken, it may give a feeling of warmth from its effect on 
the skin of the abdomen, by conduction of heat outward. 
As with other senses, a sudden change in the degree of 
the stimulus is more certain to rouse sensation than a 
gradual change. 

Reading. — The Five Senses of Man, Bernstein. 



Summary. — 1. The cutaneous sensations are touch proper, tem- 
perature sense, and pain. 

2. There are touch corpuscles in the papillae of the dermis. 

3. Touch is the most general of the senses, both in its extent in our 
bodies, and in the number of animals possessing it. 

4. Touch proper, or pressure sense, is tested by discrimination of 
additional pressure. 

5. Touch localization is tested by discrimination as to the distance 
of two points of contact. 

6. Temperature is discerned by a special set of nerve fibers. 

7. Touch and muscular sense are necessary adjuncts of sight to give 
correct perceptions of size and form. 

Questions. — 1. What is the explanation of tickling ? 

2. Where does the change occur by which we become more dis- 
criminating in the sense of touch ? 

3. Why does an emotion, such as shame, make one feel hot ? 



CHAPTER XX. 

THE SENSE OF SIGHT. 

The Sense of Sight. — In the fable of the blind man 
carrying the lame man whose eyes were good, we have an 
illustration of the dependence of the various organs on 
each other. We have considered how all our knowledge, 
both of the condition of our bodies and of the external 
world, comes through the nervous system. Now, so far 
as the senses we have studied are concerned, we learn 
almost nothing of the external world except from actual 
contact. But sight reveals objects at a distance. With- 
out the eye the body is comparatively helpless. The lame 
man that the body carries is a slight burden in comparison 
with the assistance which he renders. We can well afford 
to carry with us all the time two of these lame men to 
keep posted as to the objects beyond our reach. Of course 
touch is a great aid to our interpretations of what we see. 
But sight is evidently the main avenue of knowledge, the 
royal road along which come the messages which bring us 
the most news, which give us the keenest delight ; which 
makes us aware of most that we know of this world, and 
the only means of knowing that there are other worlds 
than the one we inhabit. 

Protection of the Eye. — The eye is set well back in 
its socket and guarded by three projecting bony promi- 
nences, — the brow, cheek bone, and the bridge of the nose. 
It is further protected by the eyelids and eyelashes. 

285 



286 PHYSIOLOGY. 

The Lacrymal Secretion. — The lacrymal gland, or 
tear gland, is just above the outer angle of the eye, and 
pours its secretion over the eyeball in weeping, or when 
there is need of an unusual supply of tears. The lids 
serve as curtains to admit or shut out light, and, by wink- 
ing, wash the eye with their own secretion, a fluid mixture 
of salt water and mucus. It is as though a man were 
kept all the time in front of a plate-glass window, with 
water and rubber scraper, to keep it clean and bright. 
The lacrymal secretion is, ordinarily, carried off as fast as 
it is made, by two ducts beginning at the inner angle of 
the eye, one on each lid ; these two ducts soon unite and 
empty by one outlet into the nasal cavity. If these ducts 
are stopped, or if the secretion be formed very rapidly, 
the liquid overflows on the face as tears. 

The External Parts of the Eye. — The "white of the 
eye" is the sclerotic coat. It has blood tubes, but ordina- 
rily they are not conspicuous. The front part of the eye- 
ball is covered with the cornea. This is transparent, and 
the color of the iris shows through the cornea. In the 
center of the iris is the hole, or pupil, by which light enters 
the interior of the eye. 

The Conjunctiva. — The front of the eyeball is covered 
by a thin, transparent, mucous membrane, the conjunctiva, 
which turns back and lines the inside of the eyelids. It is 
highly sensitive. 

The Muscles of the Eyeball. — There are six muscles which move 
the eyeball, — four straight muscles (the recti) and two oblique. The 
four straight muscles arise from the deepest part of the eye socket and 
pass forward to be attached to the top, bottom, and sides of the ball. 
Where they are attached, they are flattened out like straps. The in- 
ferior oblique arises from the inner front part of the orbit and passes 
outward to attach to the under surface of the eyeball. The superior 



THE SENSE OF SIGHT. 287 

oblique arises, like the recti, at the deeper part of the eye socket and 
passes forward through a fibro-cartilaginous loop or pulley near the 
inner, upper angle of the orbit, and then runs outward and is attached 
to the upper surface of the eyeball. 

Movements of the Eye. — These six pairs of muscles move the 
eyes to right and left, up and down, and give rotary movements. 
Normally the two eyes move in the same direction at the same time, . 
though in looking at near objects the two eyes both point inward, so 
that one appears cross-eyed, and in looking at an object that is moving 
away from one, the eyes are gradually diverging, though this is slight. 

Dissection of an Eye. — The muscles and external parts of the eye 
may readily be seen by examining the eye of a rabbit in its natural 
position and then dissecting it out. A beef eye should be obtained 
from the butcher and the structure of the eye learned by following the 
description below. 

The Coats of the Eye. — There are three coats, the outer 
or sclerotic, the middle or choroid, and the inner called the 
retina. 

The Sclerotic Coat. — This is of a dull white color, con- 
stituting the "white of the eye." It is thick and tough, 
holding all the contained parts firmly and furnishing suffi- 
cient strength for the attachment of the muscles that move 
the eyeball. 

The Choroid Coat. — The middle layer of the eye coat 
is the choroid. It is thinner than the sclerotic and of much 
more delicate structure. It is permeated by blood tubes, 
and has an inner lining of dark color to prevent the reflec- 
tion of light in the eye, just as most optical instruments 
are painted black on the inside. 

The Retina. — The retina is a continuation and expan- 
sion of the optic nerve and forms an inner coat that lines 
all but the anterior part of the eye. It is a thin, translu- 
cent film, somewhat like the film that forms over the white 



288 PHYSIOLOGY. 

of an egg when it is first dropped into hot water. It is 
exceedingly delicate and easily torn. The retina is the 
only part of the eye that is sensitive to light, and on it the 
images must be formed to produce distinct vision. 

The Cornea. — The clear front part of the eye is the 
cornea. It is a continuation of the sclerotic coat and is 

Ciliary Muscie 



Optic Nerve Choroid 

Fig 86. Horizontal Section of Right Eye. 

more bulging than the rest of the front of the eye, as can 
be seen by taking a side view of the eye, or by noticing 
some one who closes the eyelids and rolls the eyes about. 

The Iris. — This is the part that gives the color to the 
eye, or if the pigment that gives the color is lacking, the 
blood gives the pink color seen in albinos. The iris is a 
forward continuation of the choroid coat. 



THE SENSE OF SIGHT. 289 

The Pupil. — Most of the light that passes through the 
transparent cornea is stopped by the opaque iris. But in 
the center of the iris is a round hole through which light 
enters the interior of the eye. The pupil looks dark be- 
cause it is the only opening into a dark room. 

Regulation of the Amount of Light admitted into the Eye.— 

Hold a hand glass between the face and a well-lighted window. Note 
the size of the pupils. Quickly turn toward the darkest part of the 
room. We see, what we have all noticed in watching the eyes of a cat, 
that when subject to a bright light the pupil is small, but with less light 
the pupil is larger. The iris has circular muscle fibers that reduce the 
pupil when there is too much light for the eye, and when the light is 
feeble the pupil opens wider. 

The Refracting Media of the Eye. — The media that 
refract the rays of light to form the images on the retina 
are the cornea, the aqueous humor, the crystalline lens, and 
the vitreous humor. The cornea has already been described. 

The Aqueous Humor. — In looking at the entire eye it 
is not easy to realize that there is a space between the cor- 
nea and the iris. In this space is the clear, watery aque- 
ous humor. 

The Vitreous Humor. — All but the front part of the 
space within the coats of the eye is filled with a clear, 
jellylike substance, the vitreous humor. 

The Crystalline Lens. — Just back of the iris is a double- 
convex lens, clear as crystal, and of about the consistency 
of a gumdrop. It is less convex on the front surface. 

The Lens Capsule. — The lens is completely enveloped 
in a thin, transparent membrane called the lens capsule. 

The Hyaloid Membrane. — A thin membrane, the hya- 
loid membrane, lines the inner surface of the retina. As 
it continues forward toward the lens capsule it is called 
the suspensory ligament. 



290 PHYSIOLOGY. 

The Ciliary Muscle. — Arising from the sclerotic coat, 
just within the outer border of the iris, is the ciliary muscle. 
It is inserted in the margin of the lens capsule by means 
of fibrous strands that form an intimate part of the capsule. 

Experiment with Lens to show Inversion of Image. — Take a 
double-convex lens, two ot which are in the common " tripod lens, 1 ' or 




Fig. 87. The Formation of an Image on the Retina. 

any hand magnifier. Hold this up in front ot a window and catch the 
inverted image oi the window on a piece ot paper held back of the lens. 
This illustrates how the image oi an external object is formed by the 
crystalline lens upon the retina ot the eye. If two lenses of different 
thickness can be obtained, it will be seen that the thicker lens (if both 
have the same diameter) will make an image closer to the lens than the 
thinner one. 

Experiments to illustrate the Adjustment for Distance. — (i ) Stick 
a pin at each end of a book cover. Hold the book at about the usual 
distance for reading, so that the two pins are in a line with the eye. 
Look closely at the nearer pin, and the second pin will appear indistinct. 
Now look closely at the head of the farther pin. The nearer one may 
be seen, but not sharply. (2) Hold the tip of a pencil in a line with any 
object, say a picture, on a wall opposite. In looking at the tip of the 
pencil the picture is dim. Now look by the pencil at the picture, and 
the point of the pencil will be blurred. 

Adjustment of the Lens for Seeing at Different Dis- 
tances. — If we look up from a book we are reading, we 
do not realize that any change is necessary in the eye for 
us to see a distant object. But the above experiments 
prove that we cannot, at the same time, see distinctly a 
near and a distant object. When the photographer places 
his camera, he moves the ground-glass plate back and forth 
till the image is distinctly formed on the plate. We cannot 



THE SENSE OF SIGHT. 



291 



move the retina back and forth, so we change the shape of 
the lens. When we look at a near object the lens becomes 
thicker, and when we look at a distant object the lens be- 
comes less thick. This adjustment is called accommodation. 



CILIARY MUSCLE 




FAR NEAR CILIARY PROCESS 

Fig. 88. A Diagram to illustrate Accommodation. 

Action of the Ciliary Muscle. — In looking at a near object, the 
ciliary muscle pulls on the suspensory ligament, and draws it forward 
(since the muscle is fastened at the point where the iris joins the 
cornea). When the suspensory ligament is pulled forward, the lens is 
released from pressure that was given it by the lens capsule. Now the 
lens becomes thicker because it is elastic, and when it is not subject to 
pressure it tends to become relatively thick. When we look at a dis- 
tant object the muscle relaxes, and the capsule presses on the front ot 
the lens and flattens it, thus adjusting for far sight. It should be 
noted that adjustment for near sight is brought about by muscular 
effort, hence is fatiguing ; whereas adjustment for far sight is accom- 
plished mechanically, without effort. 




(2) Near-sighted Eye. (I) Normal Eye. (3) Far-sighted Eye. 

Fig. 89. Defects in Eyesight. 



Defects of Eyesight. — In old age the lens usually be- 
comes less elastic, and cannot adjust for near sight. Since 



294 PHYSIOLOGY. 

to waver. Have the pupils tell when the bright spot disappears, then 
read on, and note when the spot reappears. 

Another Experiment. — In this experiment snut the right eye, and 

be careful not to let the left eye waver. 
•^ Read this line slowly. Can you see the star all the time ? *If the 
star does not disappear before reaching the end of the line, let the eye 
travel on across the right-hand page, or hold the book nearer the face. 
In the human eye the optic nerve enters the eye not in the center, but 
nearer the nose, so that in turning the left eye toward the right at the 
proper angle, the image of the star falls upon the spot where the optic 
nerve enters. As this spot is insensitive to light, the star no longer 
appears. 

The Optic Nerve not Sensitive. — The optic nerve, 
while capable of carrying nerve impulses that cause sensa- 
tions of light, is not itself sensitive to light. If the optic 
nerve be cut, it does not give pain, but gives the sensation 
of a flash of light. 

Sympathy between the Two Eyes. — While most of 
the fibers from each optic nerve cross to the other side of 
the brain, some fibers go to the same side of the brain. 
We can therefore better understand the close sympathy 
that we know exists between the two eyes. 

Pain in the Eyes. — Pain, felt in the eyes, comes from 
impulses conveyed, not by the optic nerve, but by a branch 
of the fifth pair of nerves (the nerves of sensation for most 
of the face). 

Color Sensations. — The difference in colors is due to the differ- 
ences in the rapidity of the vibrations of the waves of light, as in sound 
differences in the rapidity of the vibrations of the sound waves cause 
the various degrees of pitch. Many interesting experiments may be 
made with color sensation, most of which are difficult of explanation. 
Fasten a bright red wafer or seal on a white card. Look intently at 
the center of the red spot till the eye is tired. Then quickiy look at 
a point in the white surface. What color appears ? This may b« 
repeated with other colors. 



THE SENSE OF SIGHT. 295 

Color Blindness. — It is found that some persons can- 
not distinguish certain colors. Blindness to red and green 
are most common. This is a matter of importance among 
railroad men and sailors where it is necessary to distinguish 
red and green signals. 

Stereoscopic Vision. — In looking at an object with one 
eye more is seen to the side of that eye, while the other 
eye sees more of the other side, considerable of the object 
being seen with both eyes. The effects produced on the 
two eyes are united, and so we better see objects as solids. 
This is what is termed stereoscopic or binocular vision. 

Duration of Impressions of Light. — Most boys have amused them- 
selves around a bonfire by whirling a stick with a glowing coal on its 
end. The continuous circle of light thus produced indicates that the 
impression of light remains for a time, in this case until the stick com- 
pletes the circle, giving a continuous line of light. Or when riding in a 
carriage the spokes of the wheels blur together because the impression 
of each lingers till another has taken its place. 

After-images. — But if we shut the eyes quickly, we may keep dis- 
tinct .the impression of the last positions, and so see them distinct from 
each other. Better still, shut the eyes while looking at the wheel, then 
open and shut them as quickly as possible. 

Again, if one looks at a bright lamp and then closes the eyes, there 
may remain the same appearance as when we looked at the object 
itself. This is called the Positive After-image. Or sometimes, espe- 
cially after looking long at a bright light, we may, on closing the eyes 
or looking away, see a dark spot of the same shape as the bright one we 
looked at. This is called the Negative After-image. 

THE CARE OF THE EYES. 

I. Objectionable Light. — In reading we wish light 
from the printed page. Hence we should avoid light 
entering the eye from any other source at this time. While 
reading, then, do not face a window, another light, a mirror, 



296 PHYSIOLOGY. 

or white wall, if it can be avoided. White walls are likely 
to injure the eyes. Choose a dark color for a covering for 
a reading table. Sewing against the background of a white 
apron has worked serious harm. Direct sunshine very 
near the book or table is likely to do harm. 

2. Position in Reference to Light. — Preferably have 
the light from behind and above. Many authors say " from 
the left," or "over the left shoulder." In writing with the 
usual slant of the letters this may be desirable. But ver- 
tical writing is now strongly advocated, as it enables one 
to sit erect, and have the light from above and equally for 
the two eyes. Sitting under and a little forward of a hang- 
ing lamp will thus give the light equally to the two eyes 
and send no light direct into the face. In reading by day- 
light avoid cross-lights so far as possible. 

3. Electric Light. — The incandescent electric light 
has an advantage in being readily lighted, without matches, 
and in giving out little heat; but owing to its irregular 
illumination (due to the shadow cast by the wire or "fila- 
ment), it is not well suited for study or other near work, 
For this purpose an Argand gas or kerosene burner is 
much to be preferred, since it throws a soft, uniform, and 
agreeable light upon the work. 

4. Reading Outdoors. — Reading out-of-doors is likely 
to injure the eyes, especially when lying down. To try to 
read while lying in a hammock is bad in many ways. Too 
much light directly enters the eye, and often too little falls 
upon the printed page. 

5. Reading Heavy Books. — Do not hold the book or 
work nearer the eyes than is necessary. So far as possible 
avoid continuous reading in large or heavy books by arti- 



THE SENSE OF SIGHT. 297 

ficial light. Such books being hard to hold, the elbows 
gradually settle down against the sides of the body, and 
thus the book is held too close to the eyes, or at a bad 
angle, or the body assumes a bad position. 

6. Resting the Eyes. — Frequently rest the eyes by 
looking up and away from the work, especially at some 
distant object. One may rest the eyes while thinking over 
each page or paragraph, and thus really gain time instead 
of losing it 

7. Strength of Light. — Have light that is strong 
enough. Remember that the law of the intensity of light 
as affected by distance is that at twice the distance the 
light is only one fourth as strong. Reading just before 
sunset is not wise. One is often tempted to go on, not 
noticing the gradual diminution of light. 

8. Evening Reading. — In all ways endeavor to favor 
the eyes by doing the most difficult reading by daylight, 
and saving the better print and the books that are easier 
to hold for work by artificial light. Writing is usually 
much more trying to the eyes than reading. By carefully 
planning his work the student may economize eyesight, 
and it is desirable that persons blessed with good eyes 
should be careful, as well as those who have a natural 
weakness in the eyes. It often results that those inherit- 
ing weak organs, by taking proper care, may outlast and 
do more and better work than those naturally stronger, 
but who, through carelessness, injure organs by improper 
use or wrong use (ab-use;. 

9. Artificial Light in the Morning. — Reading before 
breakfast by artificial light is usually bad. 



298 PHYSIOLOGY. 

10. Reading during Convalescence. — Many eyes are 
ruined during convalescence. At this time the whole sys- 
tem is often weak — including the eyes. Still, there is a 
strong temptation to read, perhaps to while away the time, 
perhaps to make up for lost time in school work. This is 
a time when a friend may show his friendship. 

1 1. Irritation of the Eyes. — If one finds himself rub- 
bing his eyes, it is a clear sign that they are irritated. It 
may be time to stop reading. At any rate, one should find 
the cause, and not proceed with the work unless the irrita- 
tion ceases. If any foreign object, as a cinder, lodges in 
the eye, it is better not to rub the eye, but to draw the lid 
away from the eyeball and wink repeatedly ; the increased 
flow of tears may dissolve and wash the matter out. To 
relieve the feeling that something must be done it may be 
well to rub the other eye, but of course this gives no posi- 
tive relief to the affected eye. If it be a sharp cornered 
cinder, rubbing may merely serve to fix it more firmly in 
the conjunctiva. If it does not soon come out, the lid may 
be rolled up over a pencil, taking hold of the lashes or the 
edge of the lid. The point of a blunt lead pencil is a con- 
venient and safe instrument with which to remove the par- 
ticle. Sometimes being out in the wind (especially if un- 
used to it), together with bright sunlight, may irritate the 
eyes. If after such exposure one finds lamplight irritating, 
he will do well to go to bed early, or remain in a dark 
room. 

12. Keep the Eyes Clean. — Be careful to keep the 
eyes clean. Do not rub the eyes with the fingers. Aside 
from consideration of rules of etiquette, there is danger of 
introducing foreign matter that may be very harmful. It 
is very desirable that each person have his individual face 



THE SENSE OF SIGHT. 299 

towel. By not observing this rule certain contagious dis- 
eases of the eyes often spread rapidly. 

13. Consult a Reliable Oculist. — If there is any con- 
tinuous trouble with the eyes, consult a reliable oculist. 
Many headaches are due to eye-strain, the real cause being 
unsuspected. If a child has frequent headaches, it is well 
to have the eyes examined. Many persons injure their 
eyes by not wearing suitable glasses. On the other hand, 
do not buy glasses of peddlers nor of any but reliable 
specialists. One may ruin the eyes by wearing glasses 
when they are not needed. Sight is priceless. 

Effects of Alcohol and of Tobacco on Sight. — Impaired 
vision is a frequent result of the use of either tobacco or 
alcoholic drink, oftener of both combined. A peculiar dis- 
ease known as the " cigarette eye " has been described as 
a dimness and film-like gathering over the eye, which ap- 
pears and disappears at intervals. It can only be cured by 
long treatment and entire disuse of tobacco. The Belgian 
government once made an investigation into the cause of the 
prevailing color-blindness, and the testimony of experts was 
that the use of tobacco was one of the principal causes. 

Reading. — Sight, Le Conte. 



Summary. — 1 . Sight, like hearing, acts through space, outstripping 
the "contact senses 1 ' of touch, taste, and smell. 

2. The eye is protected by its bony surroundings, lids, lashes, tears, 
sensitiveness of the conjunctiva, etc. 

3. The eye is moved by muscles under nerve control. 

4. The eye has three coats, — sclerotic, choroid, and retina. 

5. The pupil is a hole in the iris, and varies in size to regulate the 
amount of light admitted. 

6. The refracting media of the eye are the cornea, aqueous humor, 
lens, and vitreous humor. 



300 PHYSIOLOGY, 

7. These refracting media form an inverted image on the retina. 
The eye is a camera, darkened on the inside. 

8. The ciliary muscle, acting on the elastic lens, adjusts the lens 
for seeing at different distances. 

9. Suitable lenses overcome many of the defects in eyesight. 

10. The retina is an expansion of the optic nerve, and is exceed- 
ingly complicated in its structure. 

11. The blind spot is the place where the optic nerve enters the eye. 

12. The optic nerve is insensitive to light, but injury to it causes 
sensations of light. 

13. Most of the fibers of the optic nerve cross to the other half of 
the brain, but some do not cross. 

14. Color is due to difference in the rapidity of vibration in the 
waves of light. 

15. Eyes that do not distinguish these differences are color blind. 

16. Pain in the eyes comes through the fifth pair of nerves, not 
through the optic nerves. 

17. Binocular vision makes objects "stand out" more distinctly as 
solid bodies. 

18. Impressions of light linger, making after-images. 

19. Defects in eyesight are much more common among civilized 
men than with uncivilized men or animals. 

20. The care of the eyes must be made a subject of study and care- 
ful thought by all reading people. 

Questions. — 1 . What is the position of the eyeballs during sleep ? 

2. What is " cataract " ? 

3. What is the cause of " double vision " ? 

4. Why does the well eye sympathize with the affected one ? 

5 . Why does looking at a bright light often cause a person to sneeze ? 

6. Why is weeping associated with grief ? 

7. What is the condition of one who is "cross-eyed" ? 

8. Compare the pupils of a man, a cat, and a cow. 

9. Does the color of the eye have any relation to the strength of 
eyesight ? 

10. Why is one going from a bright room into the dark unable to 
see at first, but gradually sees more distinctly ? 

11. Why can one not see well when the eye "waters" ? 

12. If each eye has a blind spot, why are there not blank spaces in 
the field of vision ? 



CHAPTER XXI. 

TASTE, SMELL, AND HEARING. 

Uses of the Sense of Taste. — The sense of taste helps 
us in judging of the fitness of anything that presents itself 
as a candidate for election as food. By reflex action the 
taste of agreeable substances aids in digestion by stimulat- 
ing the glands, especially the salivary glands. 

The Papillae. — The surface of the tongue is covered 
with papillae. These are of three kinds. Most numerous 



Papilla 




Glosso- pharyngeal 
Nerve (9th) 



Gustatory Branch ot fifth Nerve 
Fig. 91. Diagram of Tongue, showing Nerves and Papillae. 

are the filiform papillae, slender, cylindrical projections. 
Like the papillae of the skin, they seem to be organs of 
touch. Scattered among the filiform papillae are small, 
bright red spots which, on examination, are found to be 
shaped somewhat like a mushroom, the fungiform papillae. 
Near the base of the tongue are about a dozen larger pa- 

301 



302 PHYSIOLOGY. 

pillse, arranged like a letter V with its apex toward the base 
of the tongue. These are the circumvallate papillae, each 
having around it a deep circular furrow. 

The Nerve Supply of the Tongue. — On the sides of 
this furrow are small oval bodies, called " taste buds," con- 
nected with the ends of the nerves of taste. The nerves 
of taste are the glosso-pharyngeal, or ninth cranial nerves, 
distributed to the back part of the tongue, and a branch of 
the fifth pair of nerves, the gustatory, to the front part. 

Although we ordinarily speak of an article of food as 
" palatable," or " unpalatable," the sense of taste in the 
palate is only feebly developed. The tip of the tongue 
seems to be most sensitive to sweets and salines, the back 
part to bitters, and the sides to acids. 

Solution Necessary for Tasting. — Substances must be 
dissolved before they can be tasted. If the tongue be 
wiped dry, and a few grains of salt or sugar be placed on 
it, the taste will not be perceived for a little time. Insol- 
uble substances give no taste. 

Flavors. — What we call flavors affect us more through 
the sense of smell than through taste. If the nose be held 
shut, and we are careful about breathing, a piece of onion 
placed on the tongue does not produce what we usually 
call the taste of the onion. We may thus get rid of the 
disagreeable part of taking certain medicines. Let the 
student experiment with various substances as above in- 
dicated. 

Effect of Temperature on Taste. — It is said that the 
temperature of about 40 F. is most favorable for tasting, 
and after rinsing the mouth with very hot or very cold 
water, such bitter substances as quinine will have only a 
trace of their usual taste. 



TASTE, SMELL, AND HEARING. 303 

The Sense of Smell. — "The sense of odor gives us 
information as to the quality of food and drink, and more 
especially as to the quality of the air we breathe. Hence 
we find the organ placed at the opening of the respiratory 
passages, and in close proximity to the organs devoted to 
taste. Taste is at the gateway of the alimentary canal, 
just as smell is the sentinel of the respiratory tract; and 
just as taste, when combined with smell to give the sen- 
sation we call 
flavor, influ- 
ences the di- Olfactory Bulb.. 

gestive pro- ^Mggfe^i p^';^^^ 

cess, and is olfactory Nerves- 
influenced by KK°!E£- 
it, so smell 

Turbinated Bone.- :::;;.' Ss...\.. 

influences the 
respiratory process. The 
presence of odors influ- 
ences both the amplitude 
and the number of the Pjf jf 

respiratory movements. 

„. , n r • Fig. 92. Nerves of the Outer Wall of the 

1 nus the smell ot winter- Nasal cavity. 

green notably increases the 

respiratory work, next comes ylang-ylang, and last rose- 
mary. The breathing of a fine odor is therefore not only 
a pleasure, but it increases the amplitude of the respira- 
tory movements. Just as taste and flavor influence nutri- 
tion by affecting the digestive process, and as the sight of 
agreeable or beautiful objects, and the hearing of melo- 
dious and harmonious sounds react on the body and help 
physiological well-being, so the odors of the country, or 
even those of the perfumer, play a beneficent role in the 
economy of life." — M'Kendrick and Snodgrass. 




304 PHYSIOLOGY. 

Why we Sniff. — In quiet breathing the air passes 
along the lower air passages just above the hard palate. 
The true olfactory passages are higher, but still in com- 
munication witn this lower passage. When we wish to 
test the quality of the air, we sniff, that is, make a sudden 
inspiration by jerking the diaphragm down, and an from 
the outside then rushes into these upper nasal passages, 
over the walls of which the nerves of smell, the olfactory 
nerves, are spread in the mucous membrane. The sudden 
rush of air against this membrane seems to aid greatly in 
detecting the odor. The nerves have peculiar endings, 
and it is not known just how the substances produce their 
effect. The substances must be in a very finely divided 
state, probably gaseous. The mucous membrane is sup- 
plied with mucus, and the odorous substance, probably, is 
first dissolved in the mucus. The lower, or respiratory, 
passages have a more abundant blood supply, and are 
redder than the upper. In inflammation, owing to their 
narrowness, the passages, especially the upper, are often 
closed by contact of the opposite sides. Substances like 
ammonia have no odor, but excite the tactile nerves. They 
are often spoken of as having a " pungent " odor, but are 
simply irritants. 

The Sense of Hearing. — The ear passages are inclosed 
by the hard bones of the head. The ear is, in consequence, 
difficult to dissect. It is very desirable to have a model 
of the ear. The ear may be dissected in a cat or rabbit by 
following the accompanying description. It will take time 
and patience to trace all the parts. 

The Parts of the Ear. — The ear is a much more com- 
plicated organ than would naturally be supposed. The 
parts of the ear are the external, the middle, and the in- 
ternal ear. 



TASTE, SMELL, AND HEARING. 



305 



The External Ear. — The external ear gathers the 
sound waves, and directs them into the opening of the ear, 
but the loss of the external ear does not seriously interfere 
with hearing. The passage leading inward from the ear 
extends about an inch, and is then completely shut off 
from the cavities beyond by a thin membranous partition, 
the tympanic membrane or drum skin. The skin of the 



Stirrup Anvil 



Semicircular Canals 




Fig. 93. Diagram of the Ear. 



ear dips into and lines the external tube, and continues as 
a very thin layer over the membrane of the tympanum. 
The auditory meatus, as this passageway is called, is 
guarded by hairs, and is further protected by wax secreted 
by glands of the lining. 

The Middle Ear. — Beyond the membrane of the tym- 
panum is a cavity called the middle ear. Extending across 
the cavity of the middle ear is a chain of very small bones, 
the hammer, anvil, and stirrup, the hammer being attached 



306 PHYSIOLOGY. 

to the inner surface of the membrane of the tympanum, 
and the stirrup being fastened by its base to the wall of 
the internal ear. 

The Eustachian Tube. — The middle ear communicates 
with the pharnyx by means of a narrow tube called the 
eustachian tube. It admits air to equalize the pressure on 
the two sides of the tympanic membrane. This tube is 
probably closed most of the time, but opens when we 
swallow. 

The Internal Ear. -— The internal ear consists of several 
complicated cavities and tubes which contain a liquid in 
which rest the nerves. The principal cavity is the cochlea, 
or snail-shell cavity, in which the nerve endings are con- 
nected with an exceedingly complicated apparatus. 

The Production of Sound. — Sound waves set the drum 
skin or membrane of the tympanum in vibration; the 
vibrations are conveyed by the chain of bones across 
the middle ear to the liquid of the inner ear. Through the 
complicated apparatus of the snail shell the vibrations of 
the liquid are made to start nerve impulses in the fibers of 
the auditory nerve, and when these nerve impulses are 
rightly received and interpreted by the brain, we have a 
sensation called sound. 

The Equilibrium Sense. — Probably most of the senses contribute 
to the maintaining of the equilibrium of the body by giving information 
as to position, motion, etc., especially sight and the muscular sense. 

Only that part of the auditory nerve which is distributed in the 
" snail shell " of the ear is now supposed to have to do with hearing. 
It is no longer believed that the semicircular canals are concerned with 
the process of hearing. There seems to be good evidence that the 
semicircular canals inform us as to changes of the position of the body, 
and they are regarded as the seat of an "equilibrium sense." The fact 
that one of these canals is horizontal, and that the two vertical canals 



TASTE, SMELL, AND HEARING. 307 

are at right angles to each other, strengthens this belief. It is thought 
that each of these canals detects movements in its own plane. The 
experiment has been made of placing a man on a table that easily 
turned ; with the eyes shut the subject could usually detect fairly well 
the changes of position from rotation of the table. What is known on 
the subject comes partly from observation in cases where these parts 
are diseased (which, in itself, does not cause loss of hearing), and by 
operating on lower animals ; in both of these lines of observation 
injury to these parts appears to be followed by dizziness, loss of power 
to maintain equilibrium, etc. 

The Care of the Ear. — In cleaning the ear no hard 
substance should be used ; even the finger nail is likely to 
do harm. A moistened cloth should be used. If this is 
not sufficient, a physician should be consulted. In wash- 
ing the ear it should be thoroughly dried before being 
exposed to a wind, especially a cold wind. The rapid 
evaporation may cool the parts so rapidly as to cause 
trouble. It is not well to stuff the ears with cotton. If 
there is any trouble with the hearing, of course a physician 
should be consulted without delay. 

Colds and Deafness. — A cold often produces inflam- 
mation of the mucous membrane of the pharnyx. This 
inflammation may extend along the eustachian tube to the 
middle ear and affect the hearing. 

The Use of the Ears. — The existence of an organ of 
hearing implies the existence of what? Why have we 
these organs of hearing ? Is it merely a means of protec- 
tion ? Is it that we may enjoy the music of nature, such 
as the songs of birds ? Is there not one sound that makes 
sweeter music than the most gifted of feathered songsters, 
surpassing all the instruments of man's device, even the 
violin, with its almost human flexibility and range of 
expression ? 



308 PHYSIOLOGY. 

Experiments have been made upon the sense of hearing 
which show that alcohol in small quantities injures this 
sense as it does others. 

What sound communicates to us the most of thought 
and sympathy? 

What sound was it Robinson Crusoe, in his dreary soli- 
tude, most longed to hear ? 

Reading. — The Physiology of the Senses, M'Kendrick 
and Snodgrass. 



Summary. — i . Taste enables us to judge of the quality of food, 
and it indirectly influences digestion. 

2. The tongue has two nerves of taste, the fifth pair of cranial nerves 
supplying the front, and the ninth pair the base. 

3. So-called flavors affect the sense of smell more than that of taste. 

4. The sense of smell tests food and air. 

5. Agreeable odors promote respiration. 

6. The ear consists of the outer, middle, and inner ear. In the inner 
ear are the endings of the auditory nerve. 

7. The semicircular canals have to do with a sense of equilibrium 
and not with hearing. 

8. Colds and catarrh often seriously affect hearing. 

Questions. — 1. How may the sense of taste be blunted ? 

2. What is the effect of inhaling menthol ? 

3. Does a person who is deaf in one ear hear "half as well" as 
before ? 

4. Which of the senses goes to sleep first when we go tc bed ? 

5. In what order do the other senses go to sleep ? 

6. In what order do the senses waken in the morning ? 



CHAPTER XXII 
THE VOICE. 

The Ear and the Voice. — The delicate mechanism and 
capabilities of the ear are fully matched by the fine adjust- 
ment and range of the voice. The organ of the voice is 
well worthy of study, if we look at it merely as a most 
ingenious contrivance, to say nothing of its importance to 
us as a means of expressing thought. 

"What we can learn from Our Own Throats. — We can learn a 
little from the observation of our own mouths and throats. The pro- 
jection of the throat known as " Adam's Apple " is one angle of the 
Thyroid cartilage. A ridge may be felt running downward from the 
projecting angle. Above the Adam's apple a depression may be felt. 
Press the tip of the finger lightly into this depression and perform the 
act of swallowing. It will be noted that the Adam's apple is drawn up- 
ward and closer to the bone above the depression. This bone is the 
Hyoid bone ; it is connected with the larynx below the base of the 
tongue. Below the thyroid cartilage another cartilage may be felt, 
the Cricoid cartilage. Below this is the windpipe with its rings of 
cartilage. The general form of the whole larynx may be felt in a per- 
son not overburdened with fat. 

By depressing the tongue and looking into the mouth the tip of the 
epiglottis may possibly be seen at the base of the tongue. Beyond 
these points we cannot learn much without dissection. A small mirror 
set obliquely on a handle (like those used by dentists) may be inserted 
through the mouth so that the larynx can be seen from above. But 
the meaning of what would be thus seen would not be very clear with- 
out a careful dissection of the larynx. 

The Vocal Cords. — The vocal cords are not very appro- 
priately named. They are mere ridges projecting from 

309 



3io 



PHYSIOLOGY. 



the sides of the larynx. Under the covering of mucous 
membrane are ligaments and muscles that may be stretched 
to various degrees and placed in different positions, accord- 
ing to the sound that is to be produced. 

The Position of the Vocal Cords. — While we are 
quietly breathing, the vocal cords, or bands, lie back, like 
low ridges, against the side of the larynx, and offer nearly 
the whole channel of the larynx for the free passage of air 



Epiglottis 
Base of Tongue— 




Hyoid Bone 

W$ML~\ False Vocal Cord" 

M 



Cartilage 



Trachea 




FROM RIGHT TO LEFT 



MEDIAN 



Fig. 94. Longitudinal Sections of the Larynx. 



for breathing purposes. But when we wish to produce 
vocal sound, the vocal cords are made to stand out farther 
from the side walls, and interfere with the free passage of 
the air. In examining the larynx, it is seen that the vocal 
cords are attached close to each other in front, but that at 
the back of the larynx they diverge widely (in the position 
of rest), forming a letter V, with the angle of the V in 
front, just back of Adam's apple. "When changes in the 
voice or in breathing are being made, the white glistening 





THE VOICE 311 

vocal cords may be seen to come together or to go apart 
like the blades of a pair of scissors." In a high note the 
cords are close together and nearly parallel. As the air 
is forced past the approximated edges of the vocal cords, 
they are set in vibration, and produce the sound called the 
voice. 

Illustration of the Vocal Cords. — The principle of the action of 
the vocal cords can be illustrated by the common toy known as the 
squeaking balloon, or " squawker." Here the air is driven out past a 
band of rubber stretched across the inner end of the tube. If instead 



Epiglottis 
. False Vocal Cords 

._ True Vocal Cords 



Glottis Narrowed, High Note Glottis Wider, Quiet Breathing 

Fig- 95. The Larynx, as seen by Means of the Laryngoscope, Jn Different 
Conditions of the Glottis. 

of one band with both edges free, we were to tie on the inner end of 
the tube two bands of rubber, each covering the outer edge of the tube, 
leaving the inner edge of the rubber free, and with the two bands touch- 
ing at one end and considerably separated at the other end, we would 
have a pretty fair resemblance to the larynx. 

Reenf orcement of Vocal Sound. — As in many musical 
instruments, the vibrations of the membrane alone would 
be too feeble to have much effect. In the violin, piano, 
drum, etc., the vibrations are reenforced by the vibration 
of a body of air contained within. So here the vibrations 
of the cords are reenforced and modified by the air spaces 
above. 

Loudness of Voice. — The loudness of the voice depends 
or the force with which the air is driven past the cords, 



312 PHYSIOLOGY. 

together with the size and condition of the cords them- 
selves. 

Pitch of Voice. — Pitch depends on the rapidity of the 
vibrations, which is determined by the length of the cords 
and their tension. Other things being equal, the size of 
the larynx would determine the pitch. 

Voice and Speech — The larynx by itself produces 
vocal sound merely. In speech the sounds produced in 
the larynx are much modified by the lips, tongue, teeth, 
cheeks, etc. We have voice as soon as born, but we only 
gradually acquire the power of speech. Mammals, birds, 
and some of the lower vertebrates have voices, but they 
have not speech. This distinguishes man from the ani- 
mals below him, though perhaps some of the higher apes 
have speech in a slight degree. Dogs can express their 
wants by barking, growling, snarling, etc., but it is mostly 
by their tone, with their attitudes, and a slight facial 
expression (as in snarling). 

Vowels and Consonants. — By various positions of the tongue and 
organs of the throat we make the different vowel sounds. In the con- 
sonants we more or less shut off (for the time) the passage of air, and 
so stop, or modify, the sound. This is hardly the place to study and 
analyze the sounds of our spoken language, yet it may be found profita- 
ble to watch the different organs as each sound is produced ; for when 
the structure and relation of the different parts concerned in the pro- 
duction of these sounds are better known, the definitions and state- 
ments of the books will be much more fully understood. 

Differences between Voices. — Since no two throats 
are exactly alike, no two voices sound just the same. The 
size and shape of the pharynx, the shapes and positions of 
the teeth, lips, the condition of the mucous membrane of 
the passages generally, all affect the sound, and give it its 
" quality," by which we distinguish one voice from another, 



THE VOICE. 3!3 

even if they are in the same pitch and have the same 
degree of loudness. 

Change of Voice. — At about the age of fourteen a boy's larynx 
increases in size and the voice changes, becoming deeper and heavier. 
During the change the falsetto often breaks in upon the ordinary voice ; 
the voice being said to " crack." 

Hoarseness. — If the mucous membrane covering the vocal cords is 
inflamed, or covered with too much mucous, hoarseness is likely to 
result. 

Whispering. — As in the animal we have voice without speech, so 
m whispering we have speech without voice ; that is, there is no vocali- 
zation. The organs of speech so modify the aspiration as to produce 
speech. There is no true voice. 

Culture of the Voice. — The voice and speech are 
very susceptible of culture, and nearly all voices may im- 
prove by proper cultivation. A cultivated voice and care- 
ful, distinct speech are very desirable accomplishments, 
and are not nearly so common as they ought to be. We 
delight in fine singing, and many strive to cultivate this 
art; but not so many try to learn to talk so that it is a 
pleasure to hear the spoken sound. 

Reading. — The Throat and the Voice, Cohen. 



Summary.—-!. The larynx is very complicated. Various muscles 
move the cartilages and vary the length and tension of the vocal cords, 
and thus produce the varying degrees of pitch. 

2. The vocal cords are not simple cords, but are band-like ridges 
on the sides of the larynx. 

3. The higher animals have voice but not speech. 

4. Whispering is speech without voice. 

5. The larynx is affected by " colds " and catarrh. 

Questions. — 1 * Why does one become hoarse from hearing others 
shouting? 

2. What is ventriloquism? 



CHAPTER XXIII. 
ACCIDENTS.— WHAT TO DO TILL THE DOCTOR COMES. 

How to Stop Flow of Blood from Arteries. — In case 
of bleeding from an artery the blood comes in jets. Pres- 
sure should be applied between the cut and the heart. To 
know where to apply the pressure, study of the course of 
the main arteries should be made. By studying Fig. 16 
it will be seen that the arteries to the arms pass down the 
inside of the upper arm. Here they come near the sur- 
face. At the elbow the artery is near the skin in the 
angle of the elbow. The artery which makes the pulse at 
the wrist is well known. By putting a baseball under the 
armpit and pressing the arm down firmly, the artery may 
be compressed. 

Bleeding from the Upper Arm. — In case of a deep 
cut in the lower part of the arm, a handkerchief should 
have a knot tied in it, and the knot placed over the artery ; 
that is, on the inside of the arm just below the armpit. 
Pass the handkerchief around the arm and tie it loosely. 
Then run a stick through it, and twist till the knot is drawn 
tightly against the artery. Instead of a knot, a potato, or 
anything else to make a firm lump, may be used. (See 
Figs. 1 6 and 35.) 

Bleeding from the Neck. — In studying the pulse, we 
found the Carotid artery in the neck. If a deep cut has 
been made in the upper part of the neck, it might be pos- 
sible to stop the flow by compressing the artery lower 
down the neck. 

314 



ACCIDENTS. 315 

Wounds in the Thigh. — The femoral artery comes 
near the surface in the groin. Pressure may be applied 
here in the same way to stop bleeding from a cut farther 
down the thigh. In the angle back of the knee, pressure 
may compress the artery supplying the leg. 

In case of severe wounds, pressure should be applied 
immediately to the wound. Sometimes it is well to make 
a plug of cloth and press upon the cut. 

Bleeding from Veins. — In case of bleeding from veins, 
holding the part up may check the flow. If necessary to 
apply pressure, it should be beyond the cut, instead of 
between it and the heart, as in the case of the artery. 

Hemorrhage of the Lungs or Stomach. — Blood from 
the lungs is bright, frothy, and salty ; from the stomach f 
is dark and sour. In case of bleeding from the lungs or 
stomach, let the person rest quietly on a lounge or easy- 
chair. Give him some bits of ice to swallow. 

Bleeding from the Nose. — Nosebleed may sometimes 
be stopped by pressing firmly at the base of the nose. 
Do not lean forward, as this position aids the flow. Sit 
up, and hold up the head, and hold a cloth under the nose. 
Apply cold water or ice to the nose and to the back of the 
neck. If this does not stop it, inject cold water, with a 
little salt or soda in it, into the nose. Often the flow may 

stopped by pressing firmly on the upper lip at the sides 
of the nose. If these attempts fail, a long strip of cloth 
may be used to plug the nostril, pushing the cloth in a 
little at a time, and leaving the ends so it can be pulled 
out. This should not be removed till a long time after the 
flow is checked, as it may start the bleeding afresh. After 
an attack of this kind avoid blowing the nose, as this often 
starts bleeding again. 



316 PHYSIOLOGY. 

Treatment of Burns. — Plunge the burned part into 

cold water. As soon as possible apply a solution of cook- 
ing soda (a tablespoonful of bicarbonate of soda to a tea- 
cup of water) ; or lay a wet cloth on the burned part and 
put the soda on the cloth. Afterwards apply vaseline, 
and renew the vaseline till the wound is healed. 

A mixture of equal parts of sweet oil and limewater 
makes a good liniment for dressing burns. Flour thickly 
applied gives relief, but is objectionable because it is hard 
to remove without taking the skin off with it. 

Danger from Burning Clothing. — If the clothing takes 
fire, there is added to the danger of burning the body, the 
further risk of inhaling the flame and heated air. It is 
best to lie down and roll or wrap the body in any cloths 
at hand, — rugs, shawls, etc. Running serves to fan the 
flames. Hence, if a person whose clothing is on fire is 
seen to be thoroughly frightened, and to have lost presence 
of mind and be starting to run, the best thing to do usually 
is to grasp and try to throw him to the ground, putting a 
wrap of some kind around the body at the same time if 
possible. Rolling on the ground or floor in itself would 
very likely put out a small flame. 

Treatment of Fainting. — Lay the body flat on the 
back. Keep the crowd away, and give plenty of fresh air. 
Loosen the clothing about the neck and waist. Sprinkle 
cold water on the face, but do not drench the body with a 
quantity of water. Apply smelling salts (ammonia) to the 
nostrils ; rub the limbs toward the body. If these reme- 
dies do not soon restore consciousness, send for a physician. 
A faint is not usually a serious matter. Bad ventilation, 
disagreeable odors, or even the oversweet odors of such 
flowers as the tuberose, may cause fainting. 



ACCIDENTS. 317 

Broken Bones. — Keep the patient as quiet as possible 
till the physician arrives. There need be no anxiety if the 
physician is delayed, as ordinarily no harm comes from 
waiting. If there is inflammation, cold water may be 
applied. Cooling applications are desirable in case of 
severe bruises. If it is necessary to carry the patient, lay 
him on a board, or at least keep the injured part as quiet 
as possible ; a cane or umbrella may be tied alongside a leg, 
and supported by a pillow or a coat. Sometimes the sharp 
ends of the bones may cut the flesh or even blood tubes. 

Sunstroke. — Lay the patient in the shade and pour 
cold water over the head. 




Fig. 96. Resuscitation from Drowning. (Lincoln, 3 Figures.) 
i.Position 1.) 

TREATMENT OF THE DROWNED. 

(Essentia//)/ the method recommended by the Michigan Board of Health.) 

Rule i. Remove all obstructions to breathing. Instantly 
loosen or cut apart all neck and waist bands; turn the 



3i8 



PHYSIOLOGY. 



patient on his face, with the head down hill ; stand astride 
the hips with your face toward his head, and, locking your 
fingers together under his belly, raise the body as high as 
you can without lifting the forehead off the ground (Fig. 
96, Position 1), and give the body a smart jerk to remove 
mucus from the throat and water from the windpipe,- hold 
the body suspended long enough to count slowly, one, 




Fig. 97- Resuscitation from Drowning. 
(Position 2.) 



two, three, four, five, repeating the jerk more gently two 
or three times. 

Rule 2. Place the patient on the ground face down- 
ward, and, maintaining all the while your position astride 
the body, grasp the points of the shoulders by the clothing, 
or, if the body is naked, thrust your fingers into the arm- 
pits, clasping your thumbs over the points of the shoulders^ 
and raise the chest as high as you can (Fig. 97, Position 2} 



ACCIDENTS. 



319 



without lifting the head quite off the ground, and hold it 
long enough to count slowly one, two, three. Replace 
him on the ground, with his forehead on his flexed arm, the 
neck straightened out, and the mouth and nose free. Place 
your elbows against your knees, and your hands 'upon the 
sides of his chest (Fig. 98, Position 3) over the lower ribs, 
and press downward and inward with increasing force long 





Fig. 98. Resuscitation from Drowning. 
(Position 3.) 

enough to count slowly one, two. Then suddenly let go, 
grasp the shoulders as before, and raise the chest (Position 
2), then press upon the ribs, etc. (Position 3). These al- 
ternate movements should be repeated ten or fifteen times 
a minute for an hour at least, unless breathing is restored 
sooner. Use the same regularity as in natural breathing. 

Rule 3. After breathing has commenced, restore the 
animal heat. Wrap him in warm blankets, apply bottles 



320 PHYSIOLOGY. 

of hot water, hot bricks, or anything to restore heat. Warm 
the head nearly as fast as the body lest convulsions come on. 
Rubbing the body with warm cloths or the hand, and slap- 
ping the fleshy parts, may assist to restore warmth, and 
also the breathing. If the patient can surely swallow, give 
hot coffee, tea, milk, or five grains of carbonate of ammo- 
nia in a quarter of a tumbler of hot water. Place the 
patient in a warm bed, and give him plenty of fresh air ; 
keep him quiet. 

BEWARE ! 

Avoid Delay. A moment may turn the scale for life 
or death. Dry ground, shelter, warmth, hot drinks, etc., 
at this moment are nothing — artificial breathing is 
everything — is the one remedy — all others are sec- 
ondary. 

Do not stop to remove wet clothing. Precious time is 
wasted, and the patient may be fatally chilled by the ex- 
posure of the naked body, even in summer. 

First restore Breathing. — Give all your attention and 
effort to restore breathing by forcing air into, and out of, 
the lungs. If the breathing has just ceased, a smart slap 
on the face or a vigorous twist of the hair will sometimes 
start it again, and may be tried incidentally. 

Before natural breathing is fully restored, do not let the 
patient lie on his back unless some person holds his tongue 
forward. The tongue by falling backward may close the 
windpipe and cause fatal choking. 

Prevent friends from crozvding around the patient and 
excluding the fresh air; also from trying to give drinks 
before the patient can swallow. The first causes suffoca- 
tion ; the second, fatal choking. 



ACCIDENTS. 321 

Do not give up too soon: you are working for life. 
Any time within two hours you may be on the very 
threshold of success without there being any sign of it. 

Learn to Swim. — Of course, persons who cannot swim 
well ought not to go out in a boat without taking along 
some sort of a float that may serve as a life-preserver. 
Some of the rubber cushions serve well for this. 

Every father neglects his duty if he does not teach his 
children, girls as well as boys, to swim and to float. One 
cool, trained person may save the lives of a whole boat 
load. 

When a Boat Upsets. — In case an ordinary rowboat is 
overturned, one should not attempt to climb into it or upon 
it. It takes very little to float a person in water, as the 
body is only a little heavier than water ; in fact, if a person 
fills the lungs and lies back in the water his face and nose 
will keep above water, and a person (at any rate without 
clothing) can float in this way for some time if he breathes 
lightly. The trouble is that the person tries to lift the 
whole head out of the water. The dog and such animals, 
when swimming, have little out of the water but the tip of 
the nose and a little of the top of the head. If we could 
learn something from them it would be a good thing. The 
easiest way to float is on the back. Few persons have 
been taught these facts, and most of those who have 
learned them lose their presence of mind, and waste their 
breath and strength in wild and fruitless splashing. If a 
boat be overturned, those who can swim should help those 
who cannot to get hold of the edge of the boat, but not 
permit them to climb upon it. A small plank will float a 
person if he will not try to lift much of his body out of the 
water. 



322 PHYSIOLOGY. 

Suffocation in Wells. — Persons are sometimes suffo- 
cated by carbon dioxid in wells and cisterns. Before going 
down into a well, it is a safe precaution to lower a lighted 
candle. If this is extinguished, a warning is given. If a 
second person goes down after one who has become un- 
conscious, great care must be taken that two lives are not 
lost. A rope should be firmly tied about the body, a hook, 
attached to another rope, taken to catch into the clothing 
of the first, and the rescuer should be lowered quickly and 
brought up immediately. A small rope or large cord 
might be carried, by pulling which the signal is given to 
pull up. 

In resuscitating from carbon dioxid suffocation use the 
same method as after drowning, except the first part, which 
is to remove water from the windpipe, etc. 

Poisons and their Antidotes. — Several of the common 
drugs and remedies kept about the house are more or less 
poisonous. The proper antidote for each should be known 
and kept at hand. In the first place, all such materials 
should be kept locked up so they will not be taken by 
children, or by mistake, as in the haste of getting medicine 
in the night. Again, all grown persons in the family 
should be instructed as to the effects of each poison, and 
taught its antidote. As soon as any new poisonous drug 
is bought, it should be made a point to read up about it, 
and procure an antidote. Every one should know that 
strychnin causes spasms, that opium brings on stupor, 
with contracted pupils, etc. 

Objects of Treatment. — Treatment aims at three things, 
(i) to get rid of the poison, (2) to neutralize what remains 
and prevent further action, (3) to remedy the effects already 
produced. 



ACCIDENTS. 323 

i. Mustard a Common Emetic. — The most common 
emetic is mustard ; a tablespoonful in a cup of warm water; 
give half of it, following with free drinking of warm water, 
then give the rest of the mustard. Do not wait for it to 
dissolve, but stir quickly and give at once. Provoke vom- 
iting by tickling the throat with a feather or with the 
finger. If the mouth of the patient cannot readily be 
opened, insert the thumbs inside the cheeks and back of 
the teeth. If mustard is not at hand, a strong solution of 
table salt will serve. In a few cases, such as poisoning by 
ammonia, lye, etc., it is considered best not to administer 
an emetic, but to try to neutralize the effect. 

2. Neutralize the Poison. — To neutralize a poison this 
general rule should be known : an alkali may be neutral- 
ized by an acid, and vice versa. For example, lye with 
vinegar, carbolic acid with whiting or magnesia, etc. Some 
acids and alkalis are always about a house, 

3. Give Something Soothing. — After any irritant poi- 
son some mild and soothing substance should be given, — 
white-of-egg, milk, mucilage and water, flour and water, 
gruel, olive, or castor-oil. These materials are partly for 
neutralizing the poison, and are also soothing in their 
effect. If a patient is drowsy, some stimulant may be 
given, as strong coffee (after opium). Of course a physi- 
cian should be sent for immediately, as the after-treatment 
is of great importance. 

The tables of " Poisons, their Symptoms, Antidotes, and 
Treatment," in the appendix, are taken from the excellent 
Text-Book of Nursing by Clara Weeks-Shaw. 

Wounds from Thorns, Rusty Nails. — Promote bleed- 
ing by rubbing and pressing the wound and bathing with 



324 PHYSIOLOGY. 

warm water. Or suck the wound. This tends to remove 
any injurious matter. Apply poultices. 

Bites of Cats, Dogs, etc. — If the animal is rabid (mad), suck the 
wound and cauterize quickly. A red hot poker or nail is best for cauter- 
izing. If one cannot do this promptly, use lunar caustic; strong acid 
or alkali, a coal of fire, or the coal on a cigar may be applied at once to 
the wound. Do not kill the animal if there is doubt. Keep it confined, 
and if it proves a false alarm much anxiety will be saved. After poison- 
ing with ivy, bathe the part in a mixture of two teaspoons of carbolic 
acid (pure), two tablespoons of glycerin, one half pint of water. 

Snake Bites. — If a physician is within reach, get him 
as soon as possible. The chief things to be done are (i) to 
make the wound bleed freely ; (2) to inject an antidote. 
A hypodermic syringe is needed. 

(1) Cut a slit through the wound, lengthwise of the limb, at least 
two inches long and about half an inch deep at the wound. 

(2) Make this wound bleed freely by rubbing and squeezing. Do 
not suck it. 

(3) Tie a strong cord around the limb above the wound. After a 
while this must be loosened a little from time to time. 

(4) If anti-venine is at hand, inject according to directions given 
with it. 

(5) If anti-venine is not at hand, inject, in and around the wound, 
chromic acid (1 to 100), or permanganate of potash (one five-grain 
tablet dissolved in two ounces of water). Make three injections of 
thirty minims each. If a syringe cannot be obtained, bathe the wound 
in the solution. 

(6) If the heart action becomes weak, inject into the arm fifteen or 
twenty minims of liquid strichnine. Repeat at intervals of twenty min- 
utes if needed. 

(7) If alcoholic liquor is used, only a few small doses should be 
given. A large quantity is dangerous. 

The Sick-room. — Every boy and girl ought to learn 
something about the care of the sick, as any one is 
likely to be called on to do this kind of work. Good 



ACCIDENTS. 325 

nursing is often "half the battle." In the first place, 
the nurse should faithfully follow the directions of the 
physician. This obedience should be complete as to admis- 
sion of visitors, as well as in administering medicine, etc. 
The nurse often yields to the persuasion of some unwise 
friend, " It won't do any harm for him to see me." 

Qualities of a Nurse. — The nurse should have a quick 
sympathy, and make the patient feel that all that can be 
done for his comfort will be done; yet this sympathy must 
not lead the nurse to do anything for, or give anything to 
the patient contrary to the orders of the physician. The 
nurse should always be cheerful, even when the patient 
is "impatient" and annoying in his demands. The 
patient is not "himself," and no attention should be paid 
to his unnatural irritability. 

The Room should be Cheery. — The patient should 
have a cheerful room, but the bed should be so placed 
that the light will come not too strongly into his face. 
Evidence of illness, such as medicine bottles, etc., should 
be kept out of sight so far as possible. 

Hope. — While it is not best to deceive the patient as 
to his condition, there should at all times be kept up 
an air of cheerfulness and hope. If the physician can 
inspire with confidence, and the nurse give unflagging 
good cheer, the chances of recovery are vastly improved. 
Nothing sustains like hope. 

Pure Air in the Sick-room. — Keep the air of the room 
pure. Remove excreta and everything offensive just as 
soon as possible. Do not rely on feeling as to tempera- 
ture, but keep a thermometer in the room. 

Sympathy with the Patient. — One of the necessary 
characteristics of a good nurse is the power of imagina- 



326 PHYSIOLOGY 

tion. "How would I feel, and what would I like to have 
done for me, if I were in his place?" This feeling will 
lead the nurse frequently to raise the patient's head and 
turn the pillow — the coolness of the other side of the 
pillow is refreshing; to give sips of cool water; to see 
that the patient does not suffer for want of a bath ; in 
giving a bath, to do the work thoroughly, as a skillful 
barber carefully and thoroughly reaches every fold and 
crevice back of the ear, etc. 

Bathing the Sick. — In bathing a weak person only a 
part of the body should be moistened at a time ; after this 
part is thoroughly dried, another part may be washed ; 
it is often necessary to do all this work under the bed 
clothing. 

Changing the Bedding. — In changing the bed clothing 
move the patient to one side of the bed, push the cloth- 
ing along close to his body, and place the clean bedding 
on the other side ; then move the patient back, remove 
the soiled linen, and smooth out the clean. It is often 
necessary to warm the sheets first : they should be thor- 
oughly dry. 

Follow Physician's Directions Faithfully. — Have 

the physician's directions written out plainly, as they may 
be forgotten ; and if there is a change of nurses during 
the night there is less chance of mistake. Never let your- 
self get drowsy when acting as nurse. Get up and walk 
about, get a breath of fresh air, and if inclined to be 
drowsy do not allow yourself to settle back in an easy- 
chair. If watching all night, take a good lunch in the 
middle of the night ; coffee may help to keep you awake. 
It is not to be expected that one who has worked hard 
all day out-doors will be likely to keep awake all night. 



ACCIDENTS. 327 

There should be day and night watchers, and one would 
better not watch more than six hours at a time. 

Sweeping the Sick-room. — Do not allow the room to 
be swept with the ordinary broom. The room should have 
rugs that can be removed and shaken, and the floor wiped 
with a moist cloth. If the room is carpeted, it may be 
swept with moist salt, tea-grounds or coffee-grounds, saw- 
dust, etc. Any dusting should be avoided ; furniture may 
be wiped with a damp cloth. 

Do not Whisper. — In the effort to be quiet many make 
a mistake ; do not whisper, as it disturbs more than talking, 
and also has an air of secrecy that rouses suspicion in the 
patient. 

Walk Flat-footed. — In walking on tiptoe often floors 
and stairs are made to creak when they would not in ordi- 
nary circumstances. It takes little reflection to see that 
in walking on tiptoe one brings more weight than usual 
on a smaller part of the floor, and is therefore more likely 
to spring a board in the floor ; it is best to walk flat-footed. 
Wear an easy pair of shoes ; an old pair are likely to be 
quiet. 

Food for the Sick. — Raise the head with the hand, or 
bolster the patient up, when giving drink ; or if the patient 
is very weak, use a rubber tube, so that he will not have to 
lift the head. The nurse should know how to prepare any 
food that may be needed during the night. An oil stove 
or gas stove is very desirable for cooking, or heating poul- 
tices, as an ordinary wood or coal fire is likely to die down, 
making it impossible for the nurse to do this work quickly, 
as is often necessary to take advantage of a favorable 
time, as when the patient wakens. 



328 PHYSIOLOGY, 

Care of Lamps. — Most lamps, when turned low, give 
off a disagreeable gas. It is better to have a very small 
lamp burning at full height than a large one turned low ; 
sperm candles are recommended. 

Bandaging, Preparing Food, etc. — It is well for every 
one to know something about bandaging, preparation of 
food for the sick, etc. Space here will not allow further 
treatment of these subjects, and the student is referred to 
treatises on the care of the sick, of which there are several 
good ones mentioned at the end of this chapter. 

To Prevent Sneezing. — It is well known that a sneeze 
may be prevented by firmly pressing on the upper lip. 
This may enable a nurse to keep from waking a very sick 
patient when, at a critical point, sleep is almost a question 
of life or death. And it is a convenient fact for any one 
to know. To prevent coughing there are cough drops that 
will relieve the tickling in the throat. 

For Disinfectants see Appendix. 

In addition to the list of books on Accidents, Emer- 
gencies, etc., already given, read Hand-Book of Nursing, 
published under the direction of the Connecticut Training- 
School for Nurses, State Hospital, New Haven, Conn. ; 
Text-Book of Nursing, Weeks-Shaw; Nursing: Its Prin- 
ciples and Practice, Hampton. 



Summary. — i . To stop flow of blood from an artery apply pres- 
sure to the wound, or between the wound and the heart. 

2. To stop flow of blood from a vein apply pressure to the wound or 
beyond the heart. 

3. Leaning forward promotes, instead of checking, nosebleed. 

4. To burns apply cooking soda. 

5. If the clothing takes fire lie down and roll, or wrap a rug or shawl 
about the body. 



ACCIDENTS. 329 

6. If a person with clothing on fire loses his presence of mind, seize, 
throw down, and wrap in any woolen clothing. 

7. In case of fainting lay the body flat on the back, loosen clothing, 
give fresh air, and sprinkle lightly with cold water ; if this does not 
revive, rub the limbs toward the body, hold to the nostrils smelling- 
salts (or ammonia) and, last, send for a physician. 

8. Broken bones do not urgently need prompt attention. Keep 
patient quiet and send for a physician. 

9. For resuscitation from drowning, use artificial respiration, 
promptly begun and long continued. 

10. Before going down into a well, test the air by lowering a lighted 
candle. 

11. Learn the antidotes of every poison in your house as soon as it is 
bought* and keep the antidote at hand. 

12. Volunteer to help take care of sick friends, and learn to do this 
work well. 

Questions. — 1 . How does holding up the wounded part check 
bleeding ? 

2. What other methods of resuscitation from drowning are in 
use? 

3. What are some of the poisonous substances commonly kept in 
the house? 



CHAPTER XXIV. 

THE SKELETON. 

The Two Parts of a Skeleton. — Observe that the 
skeleton as a whole consists of two portions, the axial por- 
tion, consisting of a central axis, the spinal column, to 
which the head belongs ; and the appendicular portion, 
the limbs and the bones belonging to them. 

The Uses of the Bones. — In the skeleton as a whole 
observe : — 

1. The skeleton shows the form of the body. 

2. It supports the softer tissues. 

3. It protects softer parts, as the brain in the skull, the 
spinal cord in the spinal column, the heart and lungs in 
the thorax, etc. 

4. The bones serve as levers in producing motion and 
locomotion. 

Study of a Vertebra. — Take a vertebra from the middle of the 
spinal column : — 

1. Its most solid part is its body, or centrum. 

2. On the dorsal side of this is the neural arch, forming with the 
body the neural ring, through which the spinal cord passed. 

3. From this arch there extend projections, or processes. Hold the 
vertebra by the tip of its longest process, and place it beside the cor- 
responding vertebra in the complete skeleton. Note that : — 

(a) The body is flattened where it fitted against the vertebrae 
anterior and posterior to it; 

(3) The holes in the vertebrae form a passage for the spinal cord ; 

33o 



THE SKELETON. 



331 



(c) The middle process is the spinous process, and the series of 
spinous processes form the ridge of the backbone ; 

(d) The two lateral processes are the transverse processes. 



Neural Arch 



Body . 




Transverse Process 



Spinous Process 



Fig. 99- Anterior View of Thoracic Vertebra. 
Demi-Facet for Head of Rib 



Body 




Anterior Articular 
Process 



Facet for Tubercle 
of Rib 



"•Transverse Process 



Spinous Process 




Posterior Articular Process 



Fig. 100. Left Side View of Thoracic Vertebra. 

Fit together two vertebrae in their proper order and observe that : — 
(e) The openings at the sides, through which the spinal nerves 
passed, are formed by adjacent notches, or grooves, in the contiguous 
vertebrae. 

(/") The two projections extending anteriorly from the ring of one 
vertebra fit against two corresponding processes extending posteriorly 
from the other vertebra. These are the anterior and posterior articu- 
lating processes. 



332 



PHYSIOLOGY. 



Temporal 



Frontal 



Phalanges 

\ Carpus 



Metacarpus Ulna Sternum 



Parietal 

Occipital 
Cervical Vertebrae 

Scapula 



y Thoracic Vertebrae 



Lumbar Vertebrae 




Fibula 



Metatarsus 
Fig. 101. Side View of the Human Skeleton, 



THE SKELETON. 



333 



TABLE OF THE BONES. 



Head (28) 



Skull (8) \ 



Frontal (forehead). 

2 Temporal (temples). 

2 Parietal (side). 

Occipital (posterior base). 

Sphenoid (base). 

Ethmoid (base of nose and between eyes), 



Face (14) 



2 Superior Maxillae (upper jaw). 
2 Nasal (bridge of nose). 
2 Malar (cheek). 

2 Lacrymal (inner front corner of orbit), 
2 Turbinated (within nostrils). 
2 Palate (posterior hard palate). 
Vomer (nasal partition). 
[ Inferior Maxilla (lower jaw). 



( Malleus (hammer). 
Ears (6) \ Stapes (stirrup). 
I Incus (anvil). 



Cervical Region (8) 
Thorax (37 



; 7 Cervical Vertebrae (neck). 



Hyoid Bone (base of tongue). 



f 14 True, 6 False, 4 Floating Ribs. 
\ 12 Thoracic Vertebrae (back). 
[ Sternum. 



Shoulder. 



Upper Extremities (64) \ Arm. 



Lumbar Region (5) 
Pelvis (4) 

Lower Extremities ^6o) 



J Clavicle (collar-bone). 
1 Scapula (shoulder-blade)e 
r Humerus (arm). 
\ Radius ") , c N 

I Ulna }( fore - arm )' 
( 8 Carpal (wrist). 
\ 5 Metacarpal (palm). 
I 14 Phalanges (fingers). 

5 Lumbar Vertebras (loins). 

r 2 Innominata. 

■j Sacrum. 
I Coccyx. 



Hand. 



( Thigh. Femur. 

f Patella (knee-pan). 
Leg. \ Tibia (large bone). 

*- Fibula (outer bone), 

C 7 Tarsal (instep, heel). 
Foot. \ 5 Metatarsal (arch). 

I 14 Phalanges (toes). 



334 



PHYSIOLOGY. 



The Spinal Column. — The central part of the skeleton 
is the backbone, or spinal column. As a whole it is a 
column, widening toward the base, composed of a series of 
separate bones called vertebrae. 



Hole for Blood Tubes 



Body 




Anterior Articular Facet 

..Neural Arch 



Spinous Process 



*%. Neural Ring 



Fig. 102. Anterior View of Cervical Vertebra. 



Body- 




Spinous Process 



Fig. 103. Left Side View of Cervical Vertebra. 



Each vertebra has seven processes, four articulating 
(two anterior and two posterior), two transverse, and one 
spinous. 

Take a thoracic vertebra and in the presence of the class trim off the 
processes with a pair of bone-forceps. The vertebra will be seen to be 
essentially a ring, or padlock, consisting of the body and neural ring or 
arch. 



THE SKELETON. 335 

Articulations of a Vertebra. — The smooth places where 
the articulating processes join are called facets. Observe 
on each side of the body of the vertebra a facet where the 
head of the rib articulated. There is also a facet on the 
transverse process where the tubercle of the rib articulated, 

The Cervical Vertebrae. — The seven cervical vertebrae 
(neck) have holes through their sides, or transverse pro- 
cesses, for the passage of blood tubes. 

Atlas and Axis. — The first vertebra, the atlas, has no 
body. The second vertebra is the axis. It has a peg, 
called the odontoid process, which represents the body of 
the atlas. In shaking the head, the atlas, with the head, 
turns on the axis. In nodding the head, the head simply 
rocks back and forth on the atlas. 

The Thoracic Vertebrae. — The twelve rib-supporting 
vertebrae are the thoracic vertebrae. 

The Lumbar Vertebrae. — The next five are the lumbar. 

The Sacrum and Coccyx. — The sacrum is composed of 
five vertebrae grown together, and the remaining four are 
combined in the coccyx. 

Review of the Spinal Column. — Let the eye slowly 
review the whole spinal column, noting what the vertebrae 
have in common. Note also their differences. 

Flexibility of the Spinal Column. — In most articulated 
skeletons there are pads of felt between the vertebrae. 
These take the place of the inter-vertebral cartilages, 
which are a form of connective tissue, possessing the elas- 
ticity of cartilage and the toughness of fibrous connective 
tissue, such as ligament and tendon. These inter-vertebral 



336 



PHYSIOLOGY. 



cartilages serve both to keep the vertebrae apart and to 
hold them together. When we bend the shoulders to the 
right, the right edges of these cartilages are compressed, 



Body- 



Transverse Process 




Neural Ring 
Fig. 104. Anterior View of Lumbar Vertebra. 



Body - 




Spinous 
Process 



Posterior Articular Process 
Fig. 105. Side View of Lumbar Vertebra. 

and the left edges are stretched, as a piece of india rubber 
would be if it were glued between the ends of two spools, 
and the whole were slightly bent. 

Curves of the Spinal Column. — View the spinal column 
from the side. Draw a line representing all its curves. 



THE SKELETON. 337 

The Canities of the Skeleton. — Examine the cavity vf the skull. 
If the class has not a skull which has been sawed across, look into the 
skull cavity through the hole where the spinal cord joined the brain. 

Observe the conical shape of the thorax. In the entire body the 
bones and muscles about the shoulders usually make a reversed cone of 
the upper part of the trunk. 

Observe that the ribs are connected with the breastbone by carti- 
lages. 

The upper limbs are articulated with the body only where the inner 
ends of the collar bones join the breastbone. 

Pronation and Supination. — Rest the forearm on the table with the 
palm up ; keeping the elbow fixed, turn the hand over. Turning the 
palm up is called supination ; turning it down is pronation. Perform 
this experiment with the articulated skeleton. 

The Skeleton of a Cat or Rabbit. — Examine the skeleton of a cat 
or rabbit for the sake of comparison. Note especially the skull and 
spinal column, so that you will know better what to do when dissecting 
the brain and spinal cord in one of these animals. 

The Weight of Bones. — The bones make about one sixth 
of the weight of the living body. When dried they may 
lose half of their weight. 

Microscopic Structure of Bone. i. Examine with a hand lens. — 

Hold a mounted cross-section of bone up to the light and examine with 
a hand lens. The solid part of the bone will be seen to be pierced by 
many small holes (or if the holes are filled they will appear as black 
spots) . These are the cross-sections of the haversian canals, through 
which run the blood tubes, mainly lengthwise through the bone. 

2. Examine with the Low Power of a Compound Microscope. — 

Examine the section under the microscope, using a half-inch objective. 
The bony matter will now be seen to be arranged in circles, lamella?, 
around the haversian canals, somewhat like the rings seen on the end 
of a log. 

Between the rings are circles of elongated dark dots. These are 
lacunae, cavities in which lay the live-bone corpuscles which built up 
the bone. The bone was, at first, cartilage. Later, mineral matter 
was deposited, forming true bone. 



338 



PHYSIOLOGY. 



3. Examine with a High Power. — Now examine the section 
under a one-fifth-inch objective. From the lacunae there run out, in 
every direction, little crevices, appearing as fine black lines. These 
are the canaliculi. Through the haversian canals, lacunae, and cana- 
liculi, the nourishing materials of the blood reach all parts of the bone. 

The Chemical Composition of Bone. — 1. Take a tall, narrow 
glass jar, called in the chemical laboratory a "graduate, 11 or a lamp 
chimney corked at one end answers very well, and nearly fill with 




Canaliculi Haversian Canal 

Fig. 106. Cross-section of Bone. (Highly Magnified.) 



water. Add one sixth as much hydrochloric acid. Put into this a 
slender, dry bone, such as a fibula or rib. In twenty-four hours take it 
out, rinse it thoroughly, and examine it. The acid will probably have 
dissolved out the mineral matter and left the animal matter. 

2. Lay a piece of bone on a shovel, or piece of sheet iron, and place 
in the fire. The animal matter is burned out, leaving the brittle min- 
eral ma.tter. 



THE SKELETON-. 339 

Bone is composed of mineral matter, two thirds, and animal matter, 
one third ; in childhood the animal matter is in larger proportion, while 
in old age the mineral matter is in excess. 

The mineral matter is chiefly calcium phosphate, while the animal 
matter is largely gelatin. 

Joints may be classified according to their structure as 
follows : — 

Classification of Joints. — i. Immovable, such as the 
sutures between the bones of the skull ; 

2. Mixed, such as the joints between the vertebrae; 

3. Movable, which allow free motion between the parts ; 

(a) Ball and socket, as in the hip and shoulder; 

(b) Hinge, as in the knee and elbow ; 

(c) Pivot, as in the forearm, and between the atlas and 
axis ; 

{d) Gliding, as between the short bones of the wrist, and 
of the ankle. 

Study of Joints. — Examine these joints in the articulated skeleton, 
and so far as possible, in fresh specimens (of rabbits). Compare the 
ball and socket joints of the hip and shoulder. Also compare the hinge 
joints of the knee and elbow. 

Hygiene of the Bones. — Sometimes the bones of chil- 
dren are deficient in mineral elements, and are unduly soft 
and flexible. This condition indicates a disease called 
rickets. Even if the bones are normal, children should 
not be encouraged to walk early, as bow-legs may result. 
Most bow-legged persons seem to be active, and probably 
their muscles developed faster than the bones. Constrained 
positions or excessive use of special groups of muscles may 
result in lateral curvature of the spine. The height of 
seats and desks should be carefully looked after. 

Effects of Alcohol. — Alcoholic drinks are particularly 
injurious to the young. They interfere with proper nutri- 



340 PHYSIOLOGY. 

tion and thus retard growth and development. In Europe 
a few years ago the examinations for military service 
revealed the fact that the stature of the young men 
was decreasing, and in order to secure the required num- 
ber of recruits it was necessary to lower the standard. 
Official investigation was made to ascertain the cause, 
and experts reported that it was largely due to the use of 
alcohol. 

Sprains and Dislocations. — Sprains and dislocations 
are injuries to the joints, and often bring more serious 
results than a broken bone. There should, usually, be 
complete rest until the part can be used without pain. 
Otherwise a stiffened joint may result. Hot water applied 
to a sprain or bruise promotes circulation and prevents dis- 
coloration. But if there is inflammation cold water should 
be applied. Bandages may be needed for support. 



Summary. — I . The skeleton consists of the axial and appendicular 
portions. 

2. Each vertebra consists of a body, ring (around spinal cord) and 
processes. 

3. Pads of cartilage connect the vertebrae. 

4. Bone is traversed by tubes and crevices through which it receives 
its nourishment from the blood. 

5. Bone consists of animal matter with limy matter embedded in it. 

6. Sprains should be treated carefully to avoid stiffened joints. 

Questions. — 1 . Why do the bones of old people break so much more 
easily than those of children ? 

2. What is the use of the central marrow ? 

3. What is the work of the red marrow in the spongy ends of the 
bones ? 

4. What are " sesamoid " bones ? 



CHAPTER XXV. 

THE MUSCLES. 

The Number of Muscles. — There are over five hun- 
dred muscles in the human body. These vary in size from 
less than an inch in length, in the ear and in the larynx, 
to a foot and a half long in the thigh. 

The Arrangement of Muscles. — The muscles of the 
two sides of the body are paired, and normally are about 
equal in size and strength. The muscles of the limbs are 
further paired into flexors, which bend, and the extensors, 
which straighten the limbs. The muscles are also arranged 
more or less in layers. There is generally a superficial 
layer and a more deep-seated layer. 

Forms of Muscles. — Muscles are of various shapes. 
The prevailing form in the limbs is spindle-shaped, or fusi- 
form. This is convenient, as the thicker middle portion 
of the muscle is opposite the more slender part of the 
bone, while the tendons at the ends of the muscles are 
opposite the enlarged ends of the bones at the joints. 
Some muscles are flat, some have their fibers arranged 
like the barbs of a feather, and are hence called penni- 
form. Some muscles have a tendon in the middle which 
runs through a loop, as in the case of the muscle which 
depresses the lower jaw. As already stated, muscles 
which close openings are circular, and are called sphincter 
muscles. 

34* 



342 



PHYSIOLOGY. 




■Extensors of the Hand 
•Flexors of the Hand 

Triceps 
Biceps 

■ 

Serratus Magnus 

S -. Rectus Abdominalis 

1 : ill 

fajT s ^ s 

Rectus Femoris ••ill 1 

I 

1 Vastus Externus 

Tibialis Anticus \- I 

I 

H \||\vP Extensors of the Toes 

mm 
II 

Fig. 107. Ventral View of the Superficial Muscles. 




THE MUSCLES. 



343 



Extensors of the Hand 



Triceps 



Latissimus Dorsi — 



Gluteus Maximus 



Vastus Externus 



Flexors of the Foot 




Deltoid 



Flexors of the Hand 



Biceps Cruris 



Gastrocnemius 



Tendo Achillis 



Fig. 108. Dorsal View of the Superficial Muscles. 



344 



PHYSIOLOGY. 



Names of Muscles. — Some muscles are named from 
their shape, as the deltoid on the shoulder ; from position, 
pectoralis major ; from their supposed action, as sartorius 
and adductor ; direction, as rectus, etc. The biceps and 
triceps are named from their division at their origins. 

Peculiar Muscles. — The diaphragm is a sheet of muscle 
that forms a partition between the chest and the abdomen. 
It is arched, and has a clear tendinous center. The ab- 
dominal muscles form a wall to hold the organs of the 
abdominal cavity. These muscles also aid in breathing, 
especially in forced expiration, as after violent exercise 
and in coughing. The abdominal wall consists of several 

layers of muscle. 

Heart Muscle. — The fibers 
which make up heart muscle 
are different in appearance from 
either the striated or smooth 
muscle fibers. They are more 
or less branched, as shown in 
the accompanying figure. No 
sheath has been found on these 
fibers. 

The Three Kinds of Muscular 
Fibers Compared. — For the 

sake of comparison, the striated 
Fig. 109. -Muscular fibers from the and unstriated muscle fibers are 

heart, magnified, showingtheir cross fa s h 0W n again, alongside the 

striae, divisions, and mnctions. 




heart muscle fibers. The stri- 



junctions. 
(Schweigger-Seidel.) 
The nuclei and cell-junctions are only 

represented on the right hand side ated fibers (of the skeleton) are 

e 18fure ' usually called " voluntary," and 

the plain fibers "involuntary." The heart muscle fibers 
are intermediate, being striated, but involuntary in their 



THE MUSCLES. 



345 



action. A striated muscle fiber may be I \ inches long and 
2~§-o °f an mcn wide, though usually less. The heart muscle 
fiber is narrower than the skeletal fiber, and the plain fiber 
very much smaller than either. (But the figures do not 
attempt to give relative proportions with any exactness.) 

Each Muscle Fiber is a Muscle Cell. — It is easily seen 
that each plain muscle fiber is a single cell, having its dis- 
tinct nucleus. The same is true of the heart muscle fibers, 




solated Fibers 




Fig. 110. — Plain (unstriatecH mus- 
cular fibers from the bladder. 



Fig. 111. — Two striated mus- 
cular fibers showing the ter- 
minations of the nerves. 



though they are not so simple, being more or less branched. 
In the development of striated muscle, when the muscular 
fibers are about to be formed, the cells from which they 
develop (called muscle plates) become elongated so that 
each cell is converted into a long protoplasmic fiber, with 
many nuclei. Most investigators agree that the striated 
fibers are produced by the elongation of single cells with 
multiplication of their nuclei, though some have thought 
that the fiber is formed by the coalescence of several cells 
end to end. 

Muscles of Expression. — The facial expression is due 
to the action of the muscles of the face, which in turn are 



346 PHYSIOLOGY. 

under control of the cranial nerves. The habitual position 
becomes somewhat " fixed," so it is true that character 
is often shown by "the looks." Cultivation of happy 
thoughts therefore tends to make one better looking. 

Muscles and Fat. — Fat fills in space between muscles, 
and, if abundant, forms a layer over the muscles. One 
notable instance is the hollow triangular space between 
the muscles of the cheek. If there is very little fat, a 
depression is seen, forming the " hollow cheeks." But 
an abundance of fat makes a corresponding elevation. 

Convulsions. — These spasmodic actions are due to dis- 
ordered action of the muscles, and, further back, to the 
disturbed action of the nervous system that controls the 
muscles. Various disturbances, such as indigestion, may 
by reflex action bring on convulsions. 

Rigor Mortis. — Rigor mortis (death stiffening) is a 
muscular rigidity due to the coagulation of muscle plasma. 
It usually sets in not long after death, the time of its 
appearance and its duration being variable. 

Some Prominent Muscles. — The deltoid on the shoul- 
der is a noticeable muscle. The biceps and triceps have 
already been studied. The calf muscle is one of the 
thickest and strongest in the body. The great muscles of 
the rump are needed to raise and hold the body up. On 
each side of the front of the neck is a muscle easily ob- 
served in thin persons. It extends down to the top of the 
breast bone. 

Sculpture and Anatomy. — The sculptor needs to be a 
thorough student of anatomy, so far as the bones and mus- 
cles are concerned. If he knows the muscles thoroughly, 
he can make them " stand out " naturally. Otherwise his 
work cannot be truly good. 



APPENDIX A. 

ANTISEPTICS AND DISINFECTANTS. 

The following is chiefly from Sternberg's Manual of Bacteriology, and 
embodies part of the report of "The Committee on Disinfectants of the 
American Public Health Association." 

Antiseptic Defined. — An antiseptic is a substance having the power to 
prevent or destroy putrefaction, or, what is the same thing, the bacteria upon 
which putrefaction depends. 

Disinfectant Defined. — A disinfectant is a substance that can destroy 
disease germs. 

Disinfection Defined. — Disinfection is the destroying of disease germs by 
means of heat, chemic substances, fumigation, or by fresh air. 

"The injurious consequences which are likely to result from such misap- 
prehension and misuse of the word ' disinfectant ' will be appreciated when it 
is known that recent researches have demonstrated that many of the agents 
which have been found useful as deodorizers or as antiseptics are entirely 
without value for the destruction of disease germs." 

An Antiseptic, but not a Disinfectant. — " This is true, for example, as 
regards the sulphate of iron, or copperas, a salt which has been extensively 
used with the idea that it is a valuable disinfectant. As a matter of fact, 
sulphate of iron in saturated solution does not destroy the vitality of disease 
germs, or the infecting power of material containing them. This salt is, 
nevertheless, a very valuable antiseptic, and its low price makes it one of the 
most valuable agents for the arrest of putrefactive decomposition." 

Extracts from the Above-Mentioned Report. 

Some Methods of Disinfecting. — "The most useful agents for the 
destruction of spore-containing infectious material are : — 

347 



348 



PHYSIOLOGY. 



i. Fire ; complete destruction by burning. 

2. Steam under pressure, 105 degrees C. (221 degrees F.), for ten minutes. 

3. Boiling in water for half an hour. 

4. Chlorid of lime ; a four per cent solution. 

5. Mercuric chlorid ; a solution of 1 : 500. 

For the destruction of material which owes its infecting power to the pres- 
ence of microorganisms not containing spores, the committee recommends : — 

1. Fire ; complete destruction by burning. 

2. Boiling in water for ten minutes. 

3. Dry heat ; 1 10 degrees C. (230 degrees F.) for two hours. 

4. Chlorid of lime ; a two per cent solution. 

5. Solution of chlorinated soda ; a ten per cent solution. 

6. Mercuric chlorid ; a solution of 1 : 2,000. 

7. Carbolic acid ; a five per cent solution. 

8. Sulphate of copper ; a five per cent solution. 

9. Chlorid of zinc ; a ten per cent solution. 

10. Sulphur dioxid ; exposure for at least twelve hours to an atmosphere 
containing at least four volumes per cent of this gas in the presence of 
moisture. 

Methods of Disinfecting. — The committee would make the following 
recommendations with reference to the practical application of these agents 
for disinfecting purposes : — 

For Excreta. — (a) In the sick room : — 

1. Chlorid of lime, four per cent. 
In the absence of spores : — 

2. Carbolic acid in solution, five per cent. 

3. Sulphate of copper in solution, five per cent. 

(&) In privy vaults : — 

1. Mercuric chlorid in solution, 1 : 500. 

2. Carbolic acid in solution, five per cent. 

(/) For the disinfection and deodorization of the surface of masses of 
organic material in privy vaults, etc. : — 

Chlorid of lime in powder. 

For Clothing, Bedding, etc. — (a) Soiled underclothing, bed linen, etc. 

1. Destruction by fire, if of little value. 

2. Boiling at least half an hour. 



ANTISEPTICS AND DISINFECTANTS. 



349 



3. Immersion in a solution of mercuric chlorid of the strength of I : 2,000 
for four hours. 

4. Immersion in a two per cent solution of carbolic acid for four hours. 

(b) Outer garments of wool or silk, and similar articles, which would be 
injured by immersion in boiling water or in a disinfecting solution : — 

1. Exposure in a suitable apparatus to a current of steam for ten minutes. 

2. Exposure to dry heat at a temperature of no degrees C. (230 de- 
grees F.) for two hours. 

(c) Mattresses and blankets soiled by the discharge of the sick : — 

1. Destruction by fire. 

2. Exposure to superheated steam, 105 degrees C. (221 degrees F.), foi 
ten minutes. (Mattresses to have the cover removed or freely exposed.) 

3. Immersion in boiling water for half an hour. 

Furniture and Articles of Wood, Leather, and Porcelain. — Washing, 

several times repeated, with : — 

1. Solution of carbolic acid, two per cent. 

For the Person. — The hands and general surface of the body of attend- 
ants of the sick, and of convalescents, should be washed with : — 

1. Solution of chlorinated soda diluted with nine parts of water, 1 : 10. 

2. Carbolic acid ; two per cent solution. 

3. Mercuric chlorid, I : 1,000. 

For the Dead. — Envelop the body in a sheet thoroughly saturated 
with : — 

1. Chlorid of lime in solution, four per cent. 

2. Mercuric chlorid in solution, I : 500. 

3. Carbolic acid in solution, five per cent. 

For the Sick Room. — (a) While occupied, wash all surfaces with : — 

1. Mercuric chlorid in solution, I : 1,000. 

2. Carbolic acid in solution, two per cent. 

(b) When vacated, fumigate with sulphur dioxid for twelve hours, burning 
at least three pounds of sulphur for every thousand cubic feet of air space in 
the room ; then wash all surfaces with one of the above-mentioned solutions, 
and afterward with soap and hot water ; finally throw open doors and win- 
dows, and ventilate freely." 



35o 



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354 PHYSIOLOGY. 

Daily Excretions. — Sweat, from 1.5 lbs. to 4.5 lbs. ; urea, about 
1 oz. ; organic matter exhaled, 3 grains ; urine, 53 oz. 

" Of the entire excreta, 32 per cent pass off by the breath ; 17 per 
cent by the skin ; 46.5 per cent by the kidneys ; 4.5 per cent by the 
alimentary canal." — Cutter. 

Number of Sweat Glands. — The number of sweat glands may 
be as high as 3,500 in a square inch, and the average is estimated at 
2,800 per square inch ; as there are about 2,500 square inches of body 
surface, it is readily computed that there are several millions of sweat 
glands. 

Number of Hairs on the Human Head. — The average number 
of hairs on the head is 120,000. They are set obliquely, and are con- 
trolled by muscles so that they may be made to stand erect, or nearly so, 
under the influence of certain emotions, as fear, anger, etc. 

Huxley and others have classified the races of men according to the 
hair, into the Ulotrichi, or crisp or woolly haired division, including 
the negroes, bushmen, etc. ; and Leiotrichi, or smooth-haired, sub- 
divided into the Australioid, the Mongoloid, the Xanthochroic, and the 
Melanochroic. 

In Europeans the hair is oval in cross-section ; in the Japanese 
and Chinese it is circular. 

Circulation. — Eate of blood flow : in the large arteries, from 12 to 
16 inches a second ; in the caval veins, about 4 inches a second ; in the 
capillaries, from 1 inch to 1.5 inches a minute. A portion of the blood 
makes the complete circulation (in a horse) in less than half a minute. 
This is found by putting some readily detected chemical into one jugular 
vein, and noting how soon it appears in the other jugular vein. The 
time necessary for all the blood to pass through the heart is estimated 
as follows : Each ventricle pumps about six ounces of blood at each 
stroke. At this rate thirty strokes, 25 to 50 seconds (or less), would 
have pumped all the blood in the body. Still, some of the blood (from 
the shorter circuits) may have been pumped twice, and some (from the 
longer routes) may not yet have been around once. And since the 
total amount of blood has been only approximately determined, these 
figures are not very accurate. 

Number of blood corpuscles to the cubic inch, about 83,000,000. 

Dr. Tanner's Forty Days' Fast (Newspaper Account). No 
Food but Water Taken. — When Dr. Tanner came to New York 
from Minnesota he weighed 184 pounds. He was six weeks making ar- 



VITAL STATISTICS. 



355 



rangements for his fast ; and when he began his experiment his weight 
was 157| pounds. He weighed 121^ pounds on the day his fast ended. 
He had therefore lost 62 J pounds since he came to the city, and 36 
pounds since he began his fast. Dr. Hammond, the well-known New 
York physician whose assertion that a forty days' fast was a physical 
impossibility led Dr. Tanner to make the attempt, came out in a card 
in the New York papers declaring that he believed the fast had been 
fairly conducted. 

On each day of his fast Dr. Tanner weighed as follows : — 



POUNDS. 

. 1574 

. 153 

• 1474 

. 1434 

. 139| 

. 136^ 

. 133 

. 132 



DAY. 
1st 

3d 

5th 

7th 

11th 

13th 

14th 

16th 

17th (8.30 p.m.) 1334 

17th (11 a.m.) 1354 

18th 1364 

19th 136 

20th (4 p.m.) 1354 

20th (5 a.m.) 135 

21st 135 

22d 1334 

26th 1324 



DAY. 

25th 

26th 

27th 

28th 

29th 

30th 

31st 

32d 

33d 

34th 

35th 

36th 

37th 

38th 

39th 

40th 



POUNDS. 

. 1314 

. 1314 

. 1304 

. 129| 



130 

128 

127* 

1264 

1264 



1254 
1224 

1214 



Cavities of the Body. — 1. Mucous cavities (open to the external 
air). Digestive tube, respiratory passages, genito-urinary passages, ex- 
ternal and middle ear, etc. 

2. Serous cavities (closed). They may all be said to be lymph cav- 
ities. They are the lymph spaces throughout the body, and the large 
spaces, called the pleural cavity around the lungs, the pericardial cavity 
around the heart, the peritoneal cavity in the abdomen, the arachnoid 
cavity around the brain, and a similar one along the spinal cord. 

3. Synovial cavities in the joints. 

4. Blood cavities, — the inside of the heart and blood tubes. 

5. Secretion cavities, — the cavities and tubes from the glands ; for 
example, the bile sac and its duct. 

6. Bone cavities. 



35^ 



PHYSIOLOGY. 



LOSSES OF THE TISSUES DURING STARVATION. 
(from experiment on a cat.) 



Fat ...... loses 93 per cent. 


Heart .... loses 44 per cent. 


Blood .... 


' 75 " 


Intestines ... "42 " 


Spleen .... 


« 71 " 


Muscles of locomo- 


Pancreas . . . 


' 64 " 


tion .... " 42 " 


Stomach . . . 


* 39 " 


Respiratory appa- 


Pharynx, gullet . 


' 34 " 


ratus ... "22 " 


Skin 


' 33 " 


Bones .... "16 " 


Kidneys .... 


' 31 " 


Eyes "10 " 


Liver 


' 52 " 


Nervous system . " 2 " 



QUANTITY OF WATER IN 1,000 PARTS. 



Teeth 100 

Bones 130 

Cartilage 550 

Muscles 750 

Ligament 768 

Brain 789 

Blood 795 

Synovia 805 



Bile 880 

Milk 887 

Pancreatic juice 900 

Urine 936 

Lymph . 960 

Gastric juice 975 

Sweat 986 

Saliva .995 



THE LOSS OF WATER FROM THE BODY. 

From the Alimentary canal (feces) 4 per cent. 

" " Lungs 20 " 

" " Skin (perspiration) 30 " 

" " Kidneys (urine) 46 " 



ELEMENTS IN THE HUMAN BODY. 



Oxygen 72.0 

Carbon 13.5 

Hydrogen 9.1 

Nitrogen 2.5 

Calcium 1.3 

Fosforus 1.15 

Sulfur 147 

Sodium 1 



Chlorin 

Fluorin 

Potassium . ■ . . . . 

Iron 

Magnesium 

Silicon 

Copper, lead, aluminum 



.085 
.08 
.026 
.01 
.0012 
.0002 
(traces) 

lbo! 



DAILY RATION OF A U. S. SOLDIER DURING THE LATE WAR. 

Bread or flour 22 

Fresh or salt beef (or pork or bacon 12 oz.) 20 

Potatoes (three times a week) 16 



VITAL STATISTICS. 



357 



Rice 1.6 oz. 

Coffee (or tea 0.24 oz.) 1.6 

Sugar 2.4 

Beans 64 gill. 

Vinegar 32 " 

Salt 16 



COMPOSITION OF FOODS. 



Beef, lean .... 


WATER. 

72 


PROTEIDS. 
19.3 


FATS. 

3.6 


CARBO- 
HYDRATES. 


SALTS 

5.1 


Beef, fat .... 


51 


14.8 


29.8 








4.4 


Mutton, lean . . . 


72 


18.3 


4.9 








4.8 


Mutton, fat ... 


53 


12.4 


31.1 








3.5 


Veal 


63 


16.5 


15.3 








4.7 


Pork, fat ... . 


39 


9.8 


48.9 








2.3 


Poultry 

Whitefish .... 


74 

78 


21 
18.1 


3.8 
2.9 








1.2 
1.0 


Salmon 


77 


16.1 


5.5 








1.4 


Eels (rich in fat) 
Oysters 


75 

75.7 


9.9 
11.7 


13.8 
2.4 








2.7 
2.7 










SUGAR. 




Milk 


86 


4.1 


3.9 


5.2 


.8 


Buttermilk . . . 


88 


4.1 


.7 


6.4 


.8 


Cream 


66 


2.7 


26.7 


2.8 


4.9 


Cheese, full . . . 


36 


28.4 


31.1 




4.5 


Cheese, skim . . . 


44 


44.8 


6.3 




4.9 


Eggs, white . . . 
Eggs, yelk . . . 

Bread 


78 
52 

37 


20.4 
16 

8.1 


30.7 
1.6 


STARCH. 
51 


1.6 
1.3 

2.3 


Flour 


15 


10.8 


2 


7 


O.S 




1.7 



COMPOSITION OF THE BLOOD. 

Water 

Solids — 

Corpuscles 130 

Proteids (of serum) 70 

Fibrin (of clot) 2.2 

Fatty matters (of serum) 1.4 

Inorganic salts 6.0 

Gases, urea, kreatin, etc. 6.4 



784 



216 
1000 



358 PHYSIOLOGY, 



COMPOSITION OF GASTRIG JUICE. 

Water 99.44 

Solids — 

Pepsin 319 

Salts 218 

Hydrochloric acid .02 

~~ .557 



100 

Fluids of the Body (Ford). — 1. Circulating fluids, — chyle, 
lymph, blood. 

2. Fluids for digestion, — saliva, gastric juice, pancreatic juice, bile, 
intestinal juice. 

3. Fluids of closed cavities, — of the arachnoid, pleural, pericardial, 
and peritoneal sacs, of joints, of the eye and ear, and of cells. 

4. Secretions for protection, — cerumen or wax, tears, fluid of mucous 
membranes, oily fluids on the surface of the body. 

5. Fluids for discharge, — intestinal secretion, renal or kidney se- 
cretion, perspiration, vapor from the lungs, etc. 

Acids and Alkalies of the Body. — Acids, — gastric juice, mu- 
cus, chyme, contents of large intestine. 

Alkalies, — saliva (or neutral), pancreatic juice, intestinal juice, 
bile (or neutral), contents of small intestine, sweat. 

Amount of Digestive Liquids. — The amount of saliva secreted 
daily is estimated at from 1 to 3 pints, of gastric juice from 10 to 20 pints, 
of bile from 2 to 3 pints. The amount of intestinal and other juices is 
difficult to estimate. But it is readily seen that a very large amount of 
liquid is daily separated from the blood to be used in the preparation of 
the food for absorption into the blood. This is to be looked upon as an 
investment. It is supposed to be reabsorbed with large returns in addi- 
tion to the prepared food ; and if anything interferes with the absorp- 
tion of the food material, especially if the secretion goes on, it is plain 
that bankruptcy will follow as surely as in the business world whenever 
there is a continual expenditure without corresponding returns. The 
condition known as "diarrhea" illustrates this condition, perhaps, as 
well as any well-known condition of the body. 

Specific Gravity of the Liquids of the Body. — As all the 

liquids of the body have dissolved and suspended in them various salts 
and other matters, they are all heavier than water. 



VITAL STATISTICS. 



359 



Alcohol and Longevity. — Investigation by Baer has shown that the 
average expectation of life among users and dealers in alcoholic liquors 
is very much shortened. The following table gives a comparative view of 
the expectation of life in those who abstained from and those who used 
alcohol : — 

EXPECTATION OF LIFE. 



AGE. 


ABSTAINERS. 


ALCOHOL USERS 


At 25, 


32.08 years, 


26.23 years. 


" 35. 


25.92 " 


20.01 " 


" 45 


19.92 " 


15.19 « 


" 55> 


1445 " 


II. 16 " 


" 65, 


9.62 " 


8.04 " 



TABLE SHOWING THE INFLUENCE OF ALCOHOL UPON THE 
MORTALITY FROM VARIOUS DISEASES. 



GENERAL MALE POPULATION. 



Brain disease, 


11.77 P er cen t 


Tuberculosis, 


30.36 


tt 


Pneumonia and pleuritis, 


9.63 


te 


Heart disease, 


1.46 


« 


Kidney disease, 


I.40 


u 


Suicide, 


2.99 


« 


Cancer, 


2.49 


«( 


Old age, 


22.49 


M 



ALCOHOL VENDERS 
1443 P er Cent « 
36.57 
II.44 

3.29 

2.1 1 

4.02 
3-70 
7.05 



GLOSSARY. 



Albumen (al-bu'-men). The white of an egg. 

Albumin (al-bu' -min) . A proteid substance, the chief constituent of 
the body. Its molecule is highly complex, and varies widely within 
certain limits in different organs and in different conditions. 

Albuminuria (al-bu'-mi-nu'-ri-a). The presence of albumin in the urine, 
indicating changes in the blood or in the kidneys. 

Amylopsin (am-i-lop'-sin) . A ferment said to exist in pancreatin. 

Anabolism (an-ab'-o-lizm). Synthetic or constructive metabolism. 
Activity and repair of function ; opposed to katabolism. 

Arbor Vitae (ar'-bor vi'-te). A term applied to the branched appear- 
ance of a section of the cerebellum. 

Argon (ar'-gon*). A newly discovered element similar to nitrogen 
(found in the air). 

Arytenoid (ar-i-te'-noid) . Resembling the mouth of a pitcher, as the 
arytenoid cartilages of the larynx. 

Atlas (at'-las). The uppermost of the cervical vertebrae (from the 
mythical Atlas who supported the Earth). 

Auricle (aw'-ri-kl). The auricles of the heart are the two cavities be- 
tween the veins and the ventricles. Also, the pinna and external 
meatus of the ear. 

Axis (ak'-sis). The second cervical vertebra, on which the head, with 
the atlas, turns. 

Bacterium (bak-te'-ri-um), pi. bacteria. A genus of microscopic fungi 
characterized by short, linear, inflexible, rod-like forms — without 
tendency to unite into chains or filaments. 

Biceps (bi'-seps). Biceps brachii, the flexor of the arm. 

Bicuspid (bi-kus'-pid) . Having two points ; the bicuspid or premolar 
teeth; the bicuspid valve, between the left auricle and the left ven- 
tricle. 

Brachial (brd'-ke-al or brak'-i-al). Pertaining to the arm. 

360 



GLOSSARY. 361 

Bronchus (brong'-kus), pi. bronchi. The two tubes into which the tra- 
chea divides opposite the third thoracic vertebra, called respectively 
the right and left bronchus. 

Caffein (kaf-e-iri). An alkaloid that occurs in the leaves and beans of 
the coffee-tree, in Paraguay tea, etc. 

Canaliculus (kan-a-lik'-u-lus), pi. canaliculi. The crevices extending 
from lacunae, through which nutrition is conveyed to all parts of 
the bone. 

Canine (ka-nin' or kd'-nln). The conical teeth between the incisors 
and the premolars. 

Capillary (kap'-i-la-ri or ka-pil'-a-ri). A minute blood-tube connecting 
the smallest ramification of the arteries with those of the veins. 

Capsule (kap'-sul). A tunic or bag that incloses a part of the body or 
an organ. 

Carbohydrate (kar-bo-hi'-drdt). An organic substance containing six 
carbon atoms or some multiple of six, and hydrogen and oxygen in 
the proportion in which they form water; that is, twice as many 
hydrogen as oxygen atoms. Starches, sugars, and gums are carbo- 
hydrates. 

Cardiac (kdr'-di-ak). Pertaining to the heart. 

Carotid (ka-rot'-id). The principal right and left arteries of the neck. 

Carpus (kar'-pus). Belonging to the wrist; as the carpal bones. 

Cartilage (kar'-ti-ldj). Gristle of various kinds, articular, etc. 

Casein (ka'-se-iii). A derived albumin, the chief proteid of milk, pre- 
cipitated by acids and by rennet at 40°C. 

Cecum (se'-kuin). The large blind pouch or cul-de-sac, in which the 
large intestine begins. 

Centrum (sen' -trum) . The center or middle part ; the body of a verte- 
bra, exclusive of the bases of the neural arches. 

Cerebellum (ser-e-bel'-um). The inferior part of the brain, lying below 
the cerebrum. 

Cerebrum (ser'-e-bruiri). The chief portion of the brain, occupying the 
whole upper part of the cranium. 

Cervical (ser'-vi-kal). Pertaining to the neck, as cervical vertebrae. 

Chordae tendineae (kor'-de). The tendinous cords connecting the 
fleshy columns of the heart with the auriculo-ventricular valves. 

Choroid (kd'-roid). The second or vascular coat of the eye, continu- 
ous with the iris in front, and lying between the sclerotic and the 
retina. 



GLOSSARY. 



Albumen (al-bu'-men). The white of an egg. 

Albumin (al-bvf -min) . A proteid substance, the chief constituent of 
the body. Its molecule is highly complex, and varies widely within 
certain limits in different organs and in different conditions. 

Albuminuria (al-bu'-mi-nu'-ri-a). The presence of albumin in the urine, 
indicating changes in the blood or in the kidneys. 

Amylopsin (am-i-lop'-sin) . A ferment said to exist in pancreatin. 

Anabolism (an-ab'-o-lizm) . Synthetic or constructive metabolism. 
Activity and repair of function ; opposed to katabolism. 

Arbor Vitae (ar'-bor m'-te). A term applied to the branched appear- 
ance of a section of the cerebellum. 

Argon (ar'-gon). A newly discovered element similar to nitrogen 
(found in the air). 

Arytenoid (ar-i-te'-noid). Resembling the mouth of a pitcher, as the 
arytenoid cartilages of the larynx. 

Atlas (at' -las). The uppermost of the cervical vertebrae (from the 
mythical Atlas who supported the Earth). 

Auricle (aw'-ri-kl). The auricles of the heart are the two cavities be- 
tween the veins and the ventricles. Also, the pinna and external 
meatus of the ear. 

Axis (ak'-sis). The second cervical vertebra, on which the head, with 
the atlas, turns. 

Bacterium (bak-te'-ri-um), pi. bacteria. A genus of microscopic fungi 
characterized by short, linear, inflexible, rod-like forms — without 
tendency to unite into chains or filaments. 

Biceps (bi'-seps). Biceps brachii, the flexor of the arm. 

Bicuspid (bi-kus'-pid). Having two points ; the bicuspid or premolar 
teeth; the bicuspid valve, between the left auricle and the left ven- 
tricle. 

Brachial (brd'-ke-al or brak'-i-al). Pertaining to the arm. 

360 



GLOSSARY. 361 

Bronchus (brong'-kus), pi. bronchi. The two tubes into which the tra- 
chea divides opposite the third thoracic vertebra, called respectively 
the right and left bronchus. 

Caffein (kaf-e-iri). An alkaloid that occurs in the leaves and beans of 
the coffee-tree, in Paraguay tea, etc. 

Canaliculus (kan-a-lik'-u-lus), pi. canaliculi. The crevices extending 
from lacunae, through which nutrition is conveyed to all parts of 
the bone. 

Canine (ka-ninf or ka'-nin). The conical teeth between the incisors 
and the premolars. 

Capillary (kap' -i-la-ri or ka-pil' -a-ri) . A minute blood-tube connecting 
the smallest ramification of the arteries with those of the veins. 

Capsule (kap'-sul). A tunic or bag that incloses a part of the body or 
an organ. 

Carbohydrate (kar-bo-hi'-drat). An organic substance containing six 
carbon atoms or some multiple of six, and hydrogen and oxygen in 
the proportion in which they form water; that is, twice as many 
hydrogen as oxygen atoms. Starches, sugars, and gums are carbo- 
hydrates. 

Cardiac (kar'-di-ak'). Pertaining to the heart. 

Carotid (ka-rot'-id). The principal right and left arteries of the neck. 

Carpus (kar'-pus). Belonging to the wrist; as the carpal bones. 

Cartilage (kdr'-ti-laj). Gristle of various kinds, articular, etc. 

Casein (kd'-se-iii). A derived albumin, the chief proteid of milk, pre- 
cipitated by acids and by rennet at 40°C. 

Cecum (se'-kum). The large blind pouch or cul-de-sac, in which the 
large intestine begins. 

Centrum (sen'-trum). The center or middle part ; the body of a verte- 
bra, exclusive of the bases of the neural arches. 

Cerebellum (ser-e-bel'-um). The inferior part of the brain, lying below 
the cerebrum. 

Cerebrum (ser'-e-brum). The chief portion of the brain, occupying the 
whole upper part of the cranium. 

Cervical (ser'-vi-kal). Pertaining to the neck, as cervical vertebrae. 

Chordae tendineae (kor'-de). The tendinous cords connecting the 
fleshy columns of the heart with the auriculo-ventricular valves. 

Choroid (ko'-roid). The second or vascular coat of the eye, continu- 
ous with the iris in front, and lying between the sclerotic and the 
retina. 



362 GLOSSARY. 

Chyle (kit). The milk-white fluid absorbed by the lacteals during di- 
gestion. 

Chyme {kirn). Food that has undergone gastric digestion, and has not 
yet been acted upon by the biliary, pancreatic, and intestinal 
secretions. 

Cilium (sil'-i-um), pi. cilia. The eyelashes ; also the hair-like appen- 
dages of certain epithelial cells, whose function is to propel fluid 
or particles along the passages that they line. 

Ciliary (sil'-i-a-ri). Pertaining to the eyelid or eyelash ; also by ex- 
tension to the ciliary apparatus or the structure related to the 
mechanism of accommodation. Pertaining to the cilia. 

Circumvallate (sir-kum-vaV-at). Surrounded by a wall or prominence, 
as the circumvallate papillae on the tongue. 

Clavicle (klav'-i-kl). The collar-bone. 

Coccyx (kok'-siks). The last bone of the spinal column, formed by the 
union of four rudimentary vertebrae. 

Cochlea (kok'-le-a). A cavity of the internal ear, resembling a snail- 
shell. 

Conjunctiva (kon-jungk-ti'-va). The mucous membrane covering the 
anterior portion of the globe of the eye, reflected on, and extending 
to, the free edge of the lids. 

Corpus Arantii (kor'-pus). The tubercles, one in the center of each 
segment of the semilunar valves. 

Corpuscle (kor'-pus-l). A name loosely applied to almost any small, 
rounded or oval body, as the blood corpuscles. 

Cortex (kor'-teks). Bark. The outer layer of gray matter of the brain ; 
the outer layer, cortical substance, of the kidney. 

Cricoid (kri'-koid). Eing-shaped, as the cricoid cartilage of the 
larynx. 

Dentine {den' -tin). The ivory-like substance constituting the bulk of 
the tooth, lying under the enamel of the crown and the cement 
of the root. 

Diabetes {di-a-be'-tez). The name of two different affections, diabetes 
mellitus, or persistent glycosuria, and diabetes insipidus, or polyu- 
ria, both characterized, in ordinary cases, by an abnormally large 
discharge of urine. The former is distinguished by the presence 
of an excessive quantity of sugar in the urine. 

Dialysis (di-al'-i-sis). The operation of separating crystalline from 
colloid substances by means of a porous diaphragm, the former 



GLOSSARY. 363 

passing through the diaphragm into the pure water upon which the 
dialyzer rests. 

Digastric (di-gas'-trik). Having two bellies, as the digastric muscle, 
enlarged near each end and with a tendon in the middle. 

Duodenum (du-o-de'-num). The first part of the small intestine, begin- 
ning with the pylorus. 

Emulsion (e-mul'-shun). Water or other liquid in which oil, in minute 
subdivision of its particles, is suspended. 

Enamel (en-am'-el). The hard covering of the crown of a tooth. 

Endothelium (en-do-the'-li-um). The internal lining membrane of 
serous, synovial, and other internal surfaces, the homolog of epi- 
thelium. 

Enzyme (en'-zim). Any chemic or hydrolytic ferment, as distinguished 
from organized ferments such as yeast ; unorganized ferment. 

Epiglottis (ep-i-glot'-is). A thin fibrocartilaginous valve that aids in 
preventing food and drink from passing into the larynx. 

Esophagus (e-sof'-a-gus). The musculo-membranous tube extending 
from the pharynx to the stomach. 

Eustachian (u-sta'-ki-an). Eustachian tube, the tube leading from the 
middle ear to the pharynx. 

Facet (fas'-et). A small plane surface. The articulating surface of a 
bone. 

Femur (/e'-mer). The thigh-bone. 

Ferment (fer'-ment). Any micro-organism, proteid, or other chemic 
substance capable of producing fermentation, i.e., the oxidation 
and disorganization of the carbohydrates. 

Fibrin (fi'-brin). A native albumen or proteid, a substance that, be- 
coming solid in shed blood, plasma, and lymph, causes coagulation 
of these fluids. 

Fibula {jib'-u-la). The smaller or splint bone- in the outer part of the 
leg, articulating above with the tibia, and below with the astraga- 
lus and tibia. 

Filiform (fil'-i-form). Thread-like, as the filiform papillae. 

Frontal (fron'-tal). Belonging to the front, as the frontal bone. 

Fungiform (fun'-ji-form). Having the form of a mushroom, as fungi- 
form papillae. 

Ganglion (gang'-gli-on), pi. ganglions or ganglia. A separate and semi- 
independent nervous center, communicating with other ganglia or 
nerves, with the central nervous system, and peripheral organs. 



364 GLOSSARY. 

Gastric (gas'-trik). Pertaining to the stomach. 

Gelatin (jel'-a-tiri). An albuminoid substance of jelly-like consistence, 
obtained by boiling skin, connective tissue, and bones of animals 
in water. The glue of commerce is an impure variety. 

Glosso-pharyngeal {glos'-o-fa-rin'-je-al). Pertaining to the tongue and 
larynx. 

Gluten {gib' -ten). A substance resembling albumin, and with which it 
is probably identified ; it occurs abundantly in the seeds of cereals. 

Glycogen {gli'-ko-jen). A white amorphous powder, tasteless and odor- 
less, forming an opalescent solution with water, and insoluble in 
alcohol. It is commonly known as animal starch. It occurs in the 
blood and in the liver, by which it is elaborated, and is changed by 
diastasic ferments into glucose. 

Gustatory {gus'-td-to-ri). Pertaining to the special sense of taste and 
its organs. 

Hashish {hash'-esh). A preparation from Indian hemp, Cannabis in- 
dica. It is a powerful narcotic. 

Haversian {ha-ver'-zian). Haversian canal, in bone, a central opening 
for blood-tubes, surrounded by a number of concentric rings, or 
lamellae, of bone. 

Hemoglobin {hem-b-glb'-Mn). A substance existing in the corpuscles of 
the blood, and to which their red color is due. 

Hepatic {he-pat' -ik). Pertaining or belonging to the liver. 

Hilum {hi'-lum). A small pit, scar, or opening in an organic structure ; 
the notch on the internal or concave border of the kidney. 

Humerus {hu'-me-rus) . The bone of the upper arm. 

Humor {hu'-mor). Any liquid, or semi-liquid, part of the body. 

Hyoid {hi'-oid). Having the form of the letter U. The hyoid bone 
situated between the root of the tongue and the larynx, supporting 
the tongue and giving attachment to its muscles. 

Hypo-glossal {hl-pb-glos'-al). Under the tongue. 

Iliac {il'-i-ak). Pertaining to the ilium, or region of the flanks, as iliac 
artery, vein, etc. 

Incisor {in-si'-sor). The chisel-shaped front teeth. 

Inhibition {in-M-Msh'-un). The act of checking, restraining, or sup- 
pressing ; any influence that controls, retards, or restrains. Inhib- 
itory nerves and centers are those intermediating a modification, 
stoppage, or suppression of a motor or secretory act already in 
progress. 



GLOSSARY. 365 

Innominate (i-nom'-i-nate). Nameless ; a term applied to several parts 
of the body to which no other definite name has been given, as the 
innominate bone, artery, vein, etc. 

Invertin (in'-ver-tin). A ferment found in the intestinal juice, and also 
produced by several species of plants ; it converts cane-sugar in 
solution into invert sugar. 

Jugular (jb'-gu-lar). Pertaining to the throat, as the jugular vein. 

Katabolism (ka-tab'-b-lizrn). Analytic or destructive metabolism ; a 
physiologic disintegration ; opposed to anabolism. 

Lacrymal (lak'-ri-mal). Having relation to the organs of the secretion, 
transfer, or excretion of tears. 

Lacuna (la-ku'-na). A little hollow space ; especially the microscopic 
cavities in bone occupied by the bone corpuscles, and communicat- 
ing with one another and with the haversian canals and the sur- 
faces of the bone through the canaliculi. 

Lamella (la-mel'-ci), pi. lamellae. A thin lamina, scale, or plate ; of 
bone, the concentric rings surrounding the haversian canals. 

Larynx (lar'-ingks). The upper part of the air passage between the 
trachea and the base of the tongue ; the voice-box. 

Legumin (U-gu'-min). A proteid compound in the seeds of many plants 
belonging to the natural order Leguminosae (peas, beans, lentils, 
etc.). 

Lumbar (lum'-bar), pertaining to the loins, especially to the region 
about the loins. 

Lymphatic (lim-fat' -ik). Pertaining to lymph. 

Lymphatics (lim-fat'-iks). The tubes that convey lymph. 

Lymphatic glands. The glands intercalated in the pathway of the 
lymphatic tubes, through which lymph is filtered. 

Massage (ma-sazh'). A method of effecting changes in the local and 
general nutrition, action and other functions of the body, by rub- 
bing, kneading, and other manipulation of the superficial parts of 
the body by the hand or an instrument. 

Masseter (mas'-e-ter). A chewing-muscle felt on the angle of the 
jaw. 

Medullary (med'-u-la-ri). Pertaining to the medulla, or marrow ; re- 
sembling marrow. Also pertaining to the white substance of the 
brain contained within the cortical envelop of gray matter. 

Mesenteric (mez-en-ter'-ik). Pertaining to the mesentery, as artery, 
vein, etc. 



366 GLOSSARY. 

Mesentery (jnez'-en-ter-i). A fold of the peritoneum that connects cer- 
tain portions of the intestine with the dorsal abdominal wall. 

Metabolism (me-tab'-o-lizm). A change in the intimate condition of 
cells ; (1) constructive or synthetic metabolism is called Anabo- 
lism ; in anabolism, the substance is becoming more complex and 
is accumulating force ; (2) destructive or analytic metabolism is 
called Katabolism ; in katabolism there is disintegration, the mate- 
rial is becoming less complex, and there is loss or expenditure of 
force. 

Metacarpus (met-a-kdr'-pus). The bones of the palm of the hand. 

Metatarsus (met-a-tar'-sus). The five bones of the arch of the foot, 
situated between the tarsus and the phalanges. 

Mitral (mi'-tral). Resembling a miter; mitral valve, with two flaps, 
between the left auricle and the left ventricle. 

Molar (mo'-lar). Mill; the grinding-teeth. 

Mucous (mu'-kus). A term applied to those tissues that secrete mucus. 

Mucus (mu'-kus). A viscid liquid secretion of mucous membranes, 
composed essentially of mucin, holding in suspension desquamated 
epithelial cells, etc. 

Myosin {mi'-o-sin). A proteid of the globulin class, — the chief proteid 
of muscle. Its coagulation after death causes rigor mortis. 

Narcosis (nar-ko'-sis). The deadening of pain, or production of incom- 
plete or complete anesthesia by the use of narcotic agents, such as 
anesthetics, opium, and other drugs. 

Narcotic (ndr-kot'-ic). A drug that produces narcosis. 

Neural (nu'-ral). Pertaining to the nerves. 

Neuroglia (nu-rog'-li-d). The reticulated framework or skeleton-work 
of the substance of the brain and spinal cord. The term is some- 
times abbreviated to glia. 

Nucleus (nu'-kle-us). The essential part of a typical cell, usually round 
in outline, and situated in the center. 

Occipital (ok-sip'-i-tal). Pertaining to the occiput or back part of the 
head, as the occipital bone. 

Odontoid (o-don'-toid). Resembling a tooth ; the tooth-like process 
(axis) of the second cervical vertebra, on which the atlas turns. 

Olfactory (ol-fak'-to-ri). Pertaining to the sense of smell. 

Osmosis (os-md'-sis). That property by which liquids and crystalline 
substances in solution pass through porous septa ; endosmosis and 
exosmosis. 



GLOSSARY. 367 

Oxy-hemoglobin {ok-si-hem-o-glo'-bln). Hemoglobin united, molecule 
for molecule, with oxygen. It is the characteristic constituent of 
the red corpuscles to which the scarlet color of arterial blood is 
due. 

Pancreas (pan'-kre-as). A large racemose gland lying transversely 
across the dorsal wall of the abdomen. It secretes a clear liquid 
for the digestion of proteids, fats, and carbohydrates. The sweet- 
bread of animals, vulgarly called the "belly sweet-bread" in con- 
tra-distinction to the thymus, or true sweet-bread. 

Pancreatin (pan'-kre-a-tin) . The active element of the pancreatic juice. 

Papilla (pa-pil'-a), pi. papillae. Any soft, conical elevation, as papillae 
of the dermis, tongue, etc. " 

Papillary (pap'-i-la-ri). Pertaining to a papilla; papillary muscles,— 
the conic muscular columns of the heart, to which the chordae 
tendineae are attached. 

Parietal (pa-ri'-e-tal). Pertaining to the walls, as the parietal bone. 

Parotid (pa-rot'-id). Near the ear, as the parotid salivary glands. 

Patella (pa-tel'-a). The knee-pan. 

Peptone (pep'-ton). A proteid body produced by the action of peptic 
and pancreatic digestion. 

Pericardium (per-i-kar'-di-am). The closed membranous sac or cover- 
ing that envelops the heart. 

Periosteum (per-i-os'-te-um). A fibrous membrane that invests the 
surfaces of the bones, except at the points of tendinous and liga- 
mentary attachments, and on the articular surfaces where cartilage 
is substituted. 

Peristaltic (per-i-stal'-tik). The peculiar movement of the intestine 
and other tubular organs, consisting in a vermicular shortening 
and narrowing of the tube, thus propelling the contents onward. 
It is due to the successive contractions of the bundles of longitudi- 
nal and circular muscular fibers. 

Peritoneal (per-i-to-ne'-al). Pertaining to the peritoneum. 

Peritoneum (per-i-to-ne'-um). The serous membrane lining the interior 
of the abdominal cavity, and surrounding the contained viscera. 
The peritoneum forms a closed sac, but is rendered complex in its 
arrangement by numerous foldings produced by its reflection upon 
the viscera. 

Phalanges (fa-lan'-jez), plural of phalanx (fd'-langks). Any one of 
the bones of the fingers or toes. 



368 GLOSSARY. 

Pharynx (far'-ingks). The cavity back of the soft palate. It commu- 
nicates anteriorly with the posterior nares, laterally with the eusta- 
chian tubes, ventrally with the mouth, and posteriorly with the 
gullet and larynx. 

Plasma (plaz'-ma) . The original undifferentiated substance of nascent, 
living matter. The fluid part of the blood and lymph. 

Pleura (jtlo'-ra). The serous membrane which envelops the lungs, and 
which, being reflected back, lines the inner surface of the thorax. 

Plexus (plek'-sus). An aggregation of vessels or nerves forming an 
intricate net-work. 

Pneumogastric (nu-mo-gas'-trik). Pertaining conjointly to the lungs 
and the stomach, or to the pneumogastric or vagus nerve. 

Portal (por'-tal). Pertaining to the porta (gate) or hilum of an organ, 
especially of the liver, as the portal vein. 

Postcaval (post-ka'-val). Pertaining to the postcava; the postcaval 
vein, formerly called the inferior vena cava, or vena cava ascend ens. 

Precaval (pre-ka'-val). Pertaining to the precava; the anterior caval 
vein, formerly called the superior vena cava, or vena cava de- 
scendens. 

Pronation {prb-naf-shun). The turning of the palm downward. 

Protoplasm (pro'-to-plazm). An albuminous substance, ordinarily re- 
sembling the white of an egg, consisting of carbon, oxygen, nitro- 
gen, and hydrogen in extremely complex and unstable molecular 
combination, and capable, under proper conditions, of manifesting 
certain vital phenomena, such as spontaneous motion, sensation, 
assimilation, and reproduction, thus constituting the physical basis 
of life of all plants and animals. 

Ptyalin (tl'-a-lin). An amylolytic or diastasic ferment found in saliva, 
having the property of converting starch into dextrin and sugar. 

Pulmonary (pul'-mo-na-ri). Pertaining to the lungs. 

Pylorus (pi-lo'-rus). The opening of the stomach into the duodenum. 

Radius (ra'-di-us). The outer of the bones of the forearm. 

Renal (re'-nal). Pertaining to the kidneys. 

Rennin (ren'-in). An enzyme, or ferment, to whose action is due the 
curdling or clotting of milk produced upon the addition of ren- 
net. 

Retina (ret'-i-na). The chief and essential peripheral organ of vision; 
the third or internal coat or membrane of the eye, made up of the 
end organs or expansion of the optic nerve within the globe. 



GLOSSARY. 369 

Sacrum (sa'-krum). A curved triangular bone, composed of five con- 
solidated vertebrae, wedged between tbe two iliac (pelvic) bones, 
and forming tbe dorsal boundary of tbe pelvis. 

Scapula (skap'-u-la). Tbe sboulder-blade. 

Sciatic (si-at'-ik). Pertaining to tbe iscbium; tbe sciatic nerve, the 
main nerve of the thigh. 

Sclerotic (skle-rot'-ik). Hard, indurated; pertaining to the outer coat 
of the eye. 

Semilunar (sem-i-lu'-nar). Kesembling a half-moon in shape; semilu- 
nar valves, pocket-like valves at the beginning of the aorta and 
pulmonary artery. 

Serous (se'-rus). Pertaining to, characterized by, or having the nature 
of, serum. 

Serum (se'-rurri). The yellowish fluid separating from the blood after 
the coagulation of the fibrin. 

Solar plexus (so'-lar). Solar, with radiations resembling the sun. 

Sphincter (sfingk'-ter). A muscle surrounding and closing an orifice. 

Splenic (splen'-ik). Pertaining to the spleen. 

Steapsin (step'-siri). A diastasic ferment which causes fats to combine 
with an additional molecule of water and then split into glycerine 
and their corresponding acids. 

Sternum (ster'-nurri). The breast-bone. 

Subclavian (sub-kid' '-vi-an) . Situated under the collar-bone ; subcla- 
vian artery and vein. 

Sublingual (sub-ling' -gwal). Lying beneath the tongue, as sublingual 
gland. 

Submaxillary (sub-mak' -si-la-ri) . Lying beneath the lower maxilla, as 
submaxillary salivary gland. 

Supination (su-pi-na'-shun). The turning of the palm upward. 

Synovia (si-no'-vi-a). The lubricating liquid secreted by the synovial 
membranes in the joints. 

Tarsus (tdr'-sus). The instep, consisting of seven bones. 

Temporal (tem'-po-ral). Pertaining to the temples, as temporal artery, 
vein, muscle, etc. 

Tetanus (tet'-a-nus). A spasmodic and continuous contraction of the 
muscles, causing rigidity of the parts to which they are attached. 

Thein (the'-in). An alkaloid found in tea. 

Theobromin (the-o-bro'-min). A feeble alkaloid obtained from cacao- 
butter ; the essential substance found in cocoa and chocolate. 



370 GLOSSARY. 

Thyroid (thi'-roid). Shield-shaped, as the thyroid cartilage of the 
larynx. 

Tibia (tib'-i-a). The larger (inner) of the two hones of the leg, com- 
monly called the shinbone. 

Trachea (trd-ke'-a or tra'-ke-a). The windpipe. 

Triceps (tri'-seps). Triceps of the arm, the extensor of the arm, lying 
along the back of the humerus. 

Tricuspid (tri-kus'-pid) . Having three cusps or points, as the tricuspid 
valve. 

Trypsin (trip'-sin). The proteolytic ferment of pancreatic juice. 

Ulna (ul'-na). The larger (inner) of the two bones of the forearm. 

Ureter (u-re'-ter). The tube conveying the urine from the pelvis of the 
kidney to the bladder. 

Vaso-constrictor (vas'-o-kon-strik'-tor). Causing a constriction of the 
blood-vessels. 

Vaso-dilator (vas'-o-di-ld'-tor). Pertaining to the positive dilating mo- 
tility of the non-striated muscles of the vascular system. 

Vaso-motor (vas-o-mo'-tor). Serving to regulate the tension of the 
blood-vessels, as vaso-motor nerves ; including vaso-dilator and 
vaso-constrictor mechanisms. 

Ventricle (ven'-tri-kl). Applied to certain structures having a bellied 
appearance. The cavities of the heart from which the blood is 
forced out through the arteries. 

Vesicle (yes'-i-kl). A small, membranous, bladder-like formation, as 
air vesicle. 

Villus (villus), pi. villi. One of the numerous minute vascular projec- 
tions from the mucous membrane lining the small intestine, for ab- 
sorbing digested food. 

Vitreous (vit'-re-us). Glass-like, as the clear, jelly-like, vitreous humor 
of the eye. 



INDEX. 



Abdomen, cross section of, 161. 
Abdominal respiration, 95. 
Absorption, 181. 

Of fats, 182, 183. 

From stomach, 175. 
Accommodation, 291. 
Acids, indigestion, 179. 

Fatty, 179. 

In poisoning, 323. 

Tasting, 302. 
Action of large arteries, 49. 

Of gullet, 171. 

Of heart, 45 ; rhythmic, 65. 

Of diseased kidneys, 197. 

Of muscle, 9. 

Of ciliary muscle, 291. 

Reflex, 30, 32, 263. 
Adam's apple, 309. 
Adjustment of lens, 290. 
Afferent currents, 268. 

Nerve fibers, 27, 28, 32. 

Nerve roots, 33, 31. 
After-images, 295. 

Negative, 295 ; Positive, 295. 
After-pressure, 281. 
Air, complemental, 96, 97. 

Composition of, 100. 

Currents about stoves, 116. 

Expired, 102. 

Reserve, 96, 97. 

Residual, 96, 97. 

Sacs, 84, 91. 

In the sickroom, 325. 

Tidal, 96, 97. 

Vesicles, 84, 91, 103. 

Washed, 119. 
Albinos, 288. 
Albumen, 145. 



Albuminuria, 199. 
Alcohol, 208. 

In the army, 216, 217. 

And circulation, 70. 

Chemical properties, 213. 

And consumption, 112. 

And cold climates, 218. 

And crime, 222. 

Crothers, 253. 

Danger in use of, 214, 220. 

And disease, 220. 

Effects of, 194, 250, 251, 299, 308, 339. 

And endurance, 218. 

And digestion, 194. 

And energy, 22. 

And excesses, 252. 

And " fatty degeneration," 70. 

And heat, 139. 

Hamilton, 216. 

Hornaday, 217. 

Is it a food ? 218. 

Kitchener, 216. 

Luce, 260. 

Martin, 253. 

Moral deterioration, 253. 

As a narcotic, 214. 

And mental operation, 251. 

And muscular energy, 22. 

And nervous system, 250. 

As a poison, 220. 

Physical properties, 213. 

Physiological properties, 213. 

Smith, Dr. A., 251. 

As a stimulant, 214. 

And training, 22. 

In the tropics, 218. 

Woodhull, 216. 

Woodruff, 216. 



371 



372 



INDEX. 



Alcoholic beverages, 218. 
Alkalies, in digestion, 179. 

In poisoning, 323. 
Alveoli, of the lungs, 84. 
Ameba, 5. 
Amount of blood, 75. 

Of food needed, 193. 

Of perspiration, 136. 

Of saliva, 168. 
Amylopsin, 178. 
Anabolism, 203. 
Anatomy defined, 3. 

And sculpture, 346. 
Anesthetics, 254. 
Animal matter, 338, 339. 

Protoplasm, 202. 
Animals and plants, 205. 
Antidotes to poisons, 322, 347. 
Aorta, 44, 177. 
Apex beat of heart, 49. 
Apoplexy, 248. 
Appendicular skeleton, 330. 
Appendix, vermiform, 187. 
Aqueous humor, 288, 289. 
Arch, neural, 330, 331. 
Aristotle's experiment, 266. 
Arm, bleeding from, 314. 
Arrangement of teeth, 164. 

Of muscles»34i, 
Arterial muscle, exercise of, 233. 
Arteries, large, action of, 49. 

Bleeding from, 314. 

Distribution of, 44. 

And exercise, 69. 

Regulation of size, 68. 

Structure of, 51. 
Artery, carotid, 44, 314. 

Gastric, 44. 

Hepatic, 44, 177. 

Iliac, 44. 

Mesenteric, 177. 

Pancreatic, 44. 

Pulmonary, 42, 43. 

Renal, 44. 

Splenic, 44. 

Subclavian, 44. 
Articulating process, 331. 
Articulations of vertebra, 335. 
Artificial life, 1. 

Renewal of air, 116. 



Auditory center, 244, 264. 

Nerve, 239, 238, 305. 
Auricles of heart, 41, 47. 

Contraction of, 46. 
Asiatic cholera, Bacillus of, 123. 
Association fibers, 264. 
Astigmatism, 292. 
Atlas, 335. 
Axial skeleton, 330. 
Axis, 335 ; axis cylinder, 27, 28. 

Bacilli, types of, 123. 

Bacillus, of Asiatic cholera, 123. 

Of diphtheria, 123. 

Of hog cholera, 123. 

Tuberculosis, 122, 123 

Of typhoid fever, 123. 
Bacteria, 124. 

Of putrefaction, 127. 
Baking meat, 156. 

Powder bread, 189. 
Ball and socket joint, 339. 
Bandaging, 328. 
Barley, 149. 
Baseball, 229. 
Bathing, 232. 

The sick, 326 ; Time for, 233. 
Bath mits, 232. 
Baths, cold, 232 ; warm, 233. 
Beans, dried, 189. 
Bear, hibernation of, 201. 
Bedding, changing in sickroom, 326. 
Bee-stings, 324. 
Beef extract, 155. 

Tea, 155. 
Beets, 189. 

Beverages containing alcohol, 218. 
Biceps, 8, 15. 
Bicuspid teeth, 164. 
Bicycling, 230. 
Bile, 177. 

Duct, 186, 177. 

Functions of, 178. 

Sac, 160, 186. 
Bites of cats, 324; dogs, 324; snakes, 324. 
Bitters, taste of, 302. 
Blackberries, 189. 

Bleeding from arm, 314; arteries, 314; 
neck, 314; nose, 315; veins, 315. 
Blind spot, 293. 



INDEX. 



373 



Blindness, color, 295. 

Blister, 132. 

Blood, amount of, 75. 

Changes in, 106. 

Chemical reaction of, 75. 

Coagulation of, 74. 

Color of, 73. 

Composition of, 71. 

Of frog, 73. 

Gases of, 104. 

And glands, 134. 

Mixture of good and bad, 196. 

Quantity in different organs, 75. 

Renewal of, 200. v 

And river, 195. 

Specific gravity of, 75. 

Transfusion of, 81. 

Work of, 39. 
Blood-flow, and exercise, 107. 

And lymph-flow, jj, 78. 

Rate of, 59. 
Blood-pressure, of ventricle, 46. 
Blood-stream and sewer, 199. 
Blood-supply of brain, 247. 

Of stomach, 173. 
Blood-tubes joining heart, 42. 
Blowing, 96. 
Blushing, 68. 
Boats upsetting, 321. 
Body, care of, 2. 

And locomotive, 109. 

Temperature of, 108. 
Boiled milk, 189. 

Boiling meat, 156 ; boiling water, 152. 
Bone, composition of, 338. 

Corpuscles, 337. 

Lamellae of, 337. 
Bone, structure of, 18, 337. 
Bones, broken, 317. 

Of ear, 305, 306. 

Hygiene of, 339. 

Lightness and strength of, 20. 

Relation to muscles, 15. 

Table of, 333. 

Uses of, 21, 330. 

Weight of, 337. 
Bow-legs, 339. 
Boxing, 229. 
Brain, 235. 

Blood-supply of, 247. 



Brain centers, connection of, 263. 

Convolutions and intelligence, 240. 

Ganglia of, 241. 

Gray matter of, 241. 

Hemispheres of, 240. 

Location of functions, 244. 

Parts of, 235. 

Preservation of, 236. 

Rest, 246, 247. 

And sensation, 30, 243. 

The water-cushion of, 248. 

White matter of, 241. 

Work, 246. 
Bread, hot, 189. 
Breathing, effect on circulation, 98. 

Deep, 97, 98. 

Hygiene of, 97. 

Through mouth, 98. 

Restoring, 320. 

And swallowing, 170, 171. 
Broiling meat, 156. 
Broken bones, 317. 
Bronchi, 43. 
Bruises, 340. 
Bulb, hair, 130. 

Olfactory, 303. 

Spinal, 245, 246. 
Burning clothing, 316. 
Burns, treatment of, 316. 

Cabbage, 189. 

Caffein, 155. 

Cake, 189. 

Calf muscle of frog, 9. 

Camel's hump, 201. 

Canaliculi, 338. 

Canals, haversian, 337, 338. 

Canals, semicircular, 305, 306. 

Candle, heat of, 205. 

And respiration, 201. 
Cane sugar, 179. 
Canine teeth, 164. 
Capacity of lungs, 97, 96. 

Vital, 97. 
Capillaries, blood-flow in, 55 ; of frog's 
web, 52, S3 ; of lung, 91 ; of 
muscle, 54; pulmonary, 86. 
Capsule of lens, 289. 
Carbohydrate food, 147. 
Carbohydrates, 147. 



374 



INDEX. 



Carbon dioxid of air, ioo, 102 ; in blood, 
104; in breath, 102; in wells, 322. 
Care of body, importance of, 2. 

Of ears, 307. 

Of eyes, 295. 

Of lamps in sickroom, 328. 

Of the sick, 324, 325. 

Of teeth, 166. 
Carotid artery, 44, 314. 
Carpal bones, 333. 
Carpus, 332, 333. 
Cartilage, 19. 

Cricoid, 309. 

Intervertebral, 335. 

Thyroid, 309. 
Cartilages of windpipe, 86. 
Casein, 144, 145. 
Cataract, 293. 
Cats, bites from, 324. 
Cauliflower, 189. 
Cauterizing, 324. 
Cavities, lymph, 80. 

Serous, 80. 

Of skeleton, 337. 
Cavity, pulp, 163, 164. 
Cecum, 186. 
Celery, 189. 
Cells, aquatic, 79. 

Ciliated, 86. 

Division of, 5. 

Of epidermis, 53. 

Epithelial, 4. 

Fat, 130. 
Cells and lymph, 79, 200. 

Muscle, 5, 345. 

Nerve, 5, 28. 

And oxygen, 107. 

Pigment, 52, 53. 

Poisoning of, 200. 

Starvation of, 200. 

Structure of, 4. 
Center of control of circulation, 68. 

For hearing, 244, 264. 

Respiratory, 99. 

Of sensation, 243, 245. 

For speech, 245, 264. 

For vision, 264. 
Centrum, 330. 
Cerebellum, 236, 245. 
Cerebral cortex, functions of, 243. 



Cerebro-spinal system, cat, 26. 

Of man, 24, 25. 
Cerebrum, 235, 241. 
Cervical vertebrae, 332, 333. 
Cesspools, 151. 
Change of voice, 313. 
Cheese, 147, 189, 191. 
Chemical composition of bone, 338. 
Chemistry of respiration, 100. 
Children, exercise of, 228. 
Chloral hydrate, 257. 
Chloroform, 257. 
Chocolate, 155, 189, 212. 
Choking, 96. 
Cholera, Asiatic, bacillus of, 123. 

Hog, bacillus of, 123. 
Choroid coat, 287. 
Churning in the stomach, 174. 
Chyle, receptacle of, 184, 186. 
Chyme, 175. 

Cider, 211 ; fermentation of, 121, 212. 
Cigarettes, 259. 
Cigars, 258. 
Cilia, 87. 
Ciliary muscle, 290, 291. 

Process, 288. 
Ciliated cells, 86. 
Circulation and alcohol, 70. 

Control of, 64. 

Diagram of, 60, 196, 197, 198. 

In frog's web, 52, 53, 54. 

In gray matter, 249. 

In muscle, 54. 

Plan of, 60. 

Portal, 177. 

In white matter, 249. 
Circumvallate papillae, 302. 
Classification of senses, 271. 
Clavicle, 332, 333. 
Cleanliness of eyes, 298. 
Climate and alcohol, 209. 
Clothing, regulating heat, 138. 

Effect of wet, 139. 
Coagulation of blood, 74. 

Of muscle plasma, 346. 
Coat, choroid; 287. 

Sclerotic, 287. 
Coats of eye, 287 ; of stomach, 172. 
Cocaine, 257. 
Coccyx, 332, 333, 335. 



INDEX. 



375 



Cochlea, 305, 306. 
Cocoa, 155, 189. 
Coffee, 155, 189, 212. 
Cold baths, 232. 

Spots, 283. 

Taking, 231. 
Colds and deafness, 307. 
Colon, 187. 
Color blindness, 295. 

Of blood, 73, 105. 

Sensations, 294. 

Of skin, 132. 
Colored corpuscles, 71. 
Colorless corpuscles, 72. 

As germ destroyers, 126. 
Column, spinal, 334. 
Common sensations, 272. 
Compass points and touch, 281. 
Complemental air, 97. 
Composition of air, 100. 

Of blood, 71. 

Of bone, 338. 

Of sweat, 135. 
Conduction of heat, 137. 
Cones and rods, 293, 292. 
Conjunctiva, 286. 
Connective tissue, 11, 12. 
Consciousness, 243. 
Conservation of energy, 206. 
Consonants and vowels, 312. 
Constipating foods, 189. 
Constipation, 178, 188. 
Consumption, danger from, 122. 
Contraction of auricle, 46. 

Of ventricle, 46. 
Control of diaphragm, 100. 

Of mind, 247. 

Of respiration, 99. 
Convalescence and reading, 298. 
Convection of heat, 137. 
Conversation at meals, 192. 
Convolutions of brain, 233, 240. 

And intelligence, 240. 
Convulsions, 346. 
Cooking, 155. 
Coordination, 245. 

Cord, spinal, 24 ; reflex action of, 30, 32. 
Cords, tendinous, 41, 46; vocal, 309. 
Corn, 148, 189. 
Cornea, 288. 



Corpuscles of blood, 72, 53. 

Bone, 337. 

Colored, 71, 72, 104. 

Colorless, 72, 126. 

Touch, 279. 
Correlation of energy, 206. 
Cortex, cerebral, functions of, 243. 
Coughing, 95. 

Covering of brain, 235 ; of heart, 40. 
Cracked wheat, 189. 
Crackers, 189. 
Cramps, 35. 

Cranial nerves, 237, 242. 
Cream, 144. 
Cricoid cartilage, 309. 
Crime and alcohol, 208. 
Crossing of nerve fibers, 33, 243. 
Crown of tooth, 163. 
Crying, 95. 

Crystalline lens, 288, 289. 
Culture of voice, 313. 
Curdling in stomach, 174. 
Currents, afferent, 268, 269; efferent, 

268; induction, 266. 
Curvature of spine, 339. 
Custard, 189. 

Cutaneous sensations, 278. 
Cylinder, axis, 27. 

Danger of consumption, 122. 

Dead dust, 119. 

Deafness and colds, 307. 

Deep breathing, 99. 

Defects in eyesight, 291. 

Deliberation in eating, 192. 

Dental formula, 164. 

Dentine, 163, 164. 

Dermis, 132. 

Desserts, 191. 

Dextrose, 179. 

Diabetes, 199. 

Dialysis, 182. 

Diaphragm, 85, 87, 88, 177, 344. 

Control of, 99. 
Diarrhea, 231. 
Diastole, 47. 

Diet, errors of, 193; mixed, 153; one- 
sided, 153 ; proper, 154. 
Diffusion of gases, 115; of liquids, 182. 
Digestion, hygiene of, 190. 



376 



INDEX. 



Digestion, organs of, 160. 

Outline of, 187. 

Time in stomach, 175. 
Digestive tube, 159. 
Dilation of ventricle, 47. 
Diphtheria, bacillus of, 123. 
Direct heating, 118. 
Disease germs, 122. 

Of lungs, 126. 

Prevention of, 126. 
Dislocations, 339. 
Distribution of arteries, 44 ; of veins, 44. 

Of heat, 138. 
Division of cells, 5. 

Of labor, physiological, 4. 
Dogs, bites from, 324. 
Double windows, 119. 
Dreams, 266. 
Dried fish, 189. 
Drink, hot, 191. 
Drinking, 96. 

Water, 152. 
Dropsy, 80. 

Drowned, treatment of, 317. 
Drowning, resuscitation from, 317. 
Duodenum, 160. 
Dura mater, 235. 
Dust, avoiding, 124. 

Dead, 119; live, 121. 

And lungs, 120. 

Sources of, 120. 
Dusting, 125. 

Ear, bones of, 305, 306. 

Care of, 307. 

External, 305. 

Internal, 306. 

Middle, 305. 

Parts of, 305. 

Use of, 307. 
Eating between meals, 193. 

Deliberation in, 192. 

Time of, 193. 
Eddy, living^ 199. 
Efferent nerve currents, 268. 

Nerve fibers, 27, 32, 33. 
Eggs, 146. 
Electric light, 296. 
Emetic, mustard, 323. 
Emulsion, 147, 179. 



Enamel, 163, 164. 
Energy and alcohol, 208. 

Conservation of, 206. 

Correlation of, 206. 

From food, 204. 

Utilization of, 205. 
Ennui, 95. 

Entire wheat flour, 148. 
Enzymes, 169. 
Epidermis, 53, 131. 
Epiglottis, 170, 171, 310. 
Epithelial cells, 4. 
Equilibrium sense, 306. 
Errors in diet, 193. 
Essentials of reflex action, 32. 
Ethmoid bone, 333. 
Eustachian tube, 306, 305, 170, 171. 
Evaporation of sweat, 137. 
Evening reading, 297. 
Excretion, 130 ; of urea, 202. 
Exercise of arterial muscles, 233. 

And bathing, 226. 

And blood-flow, 107. 

Forms of, 228. 

And health, 226. 

And heat, 137. 

And long life, 227. 

And size of arteries, 69. 
Expiration, elastic reactions of, 94. 
Explosion in muscles, no. 
Expression, muscles of, 345. 
Extensor muscle, 8. 
External ear, 305. 
Extract of beef, 155. 
Eye, coats of, 287. 

Dissection of, 287. 

External parts of, 286. 

Movements of, 287. 

Muscles, 286, 288. 

Protection of, 285. 

Section of, 288. 

Structure of, 288. 
Eyes, of albinos, 288. 

Care of, 295. 

Cleanliness of, 298. 

Irritation of, 298; 

Pain in, 294. 

Pigment in, 288. 

Resting, 297. 

Sympathy between, 294. 



INDEX. 



377 



Eyeball, muscles of, 286. 
Eyeglasses, 292. 
Eyesight, defects of, 291. 
Eyestrain, 299. 

Facial expression, 345. 

Nerves, 238. 
Fainting, 316, 248. 
Fans, ventilating, 117. 
Far-sight, 291, 292. 
Farina, 189. 
Fat cells, 130. 

And muscles, 346. 

As a tissue, 201. 
Fats, 147. 
Fatty acids, 179. 

Fatigue, 246, 272; from standing, 268. 
Femur, 18, 332, 333. 
Fever, typhoid, 151. 
Fiber, muscle, plain, 50, 344. 

Muscle, striated, 11, 12, 344. 

Nerve, 28. 
Fibers, association, 264. 
Fibrin, 74, 145. 
Fibula, 333. 
Filiform papillae, 301. 
Fish, 146; dried fish, 189. 
Flavors, 302. 

Flexibility of spinal column, 335. 
Flexion of forearm, 16. 
Flexor muscle, 8, 13. 
Flexure, sigmoid, 188. 
Floating, 321. 

Flour, entire wheat, 148 ; Graham, 148. 
Flow of lymph, 77. 
Flues, ventilating, 115. 
Food, amount needed, 193. 

Object of, 159. 

Regulating temperature, 138. 

For the sick, 327. 

Source of energy, 204. 
Foods, 144. 

Constipating, 189 ; laxative, 189. 

Preservation of, 127. 
Foodstuffs, 144, 145. 
Foot asleep, 37 ; as kind of lever, 17. 
Football, 229. 

Force, indestructibility of, 204. 
Forced respiration, 94. 
Forms of exercise, 228 ; of muscles, 341. 



Formula, dental, 164. 
Foul air shafts, 117. 
Frog, blood of, 73. 

Without cerebrum, 241. 

Muscle action of, 9. 
Frontal bone, 332, 333. 
Fruits, 150. 

Acid, 189. 

Pies, 189. 

Puddings, 189. 
Frying, 156. 
Fulcrum, 16. 
Function, defined, 3. 

Of cerebellum, 245. 

Of cerebral cortex, 243. 

Of cerebrum, 241. 

Of nerve fibers, 28. 

Of nerve roots, 33. 

Of skin, 136. 

Of spinal bulb, 245. 

Of spinal cord, 29. 
Fungiform papillae, 301. 
Furnaces, 117. 

Gain and loss of body, 195. 
Game, wild, 189. 
Games of children, 228. 
Ganglia, 29; of brain, 241. 

Sympathetic, 65. 
Ganglion of dorsal root, 26, 29. 
Gargling, 95. 
Gases of blood, 104. 

Diffusion of, 115. 
Gastric glands, 173 ; juice, 173, 174. 
Gelatin, 145. 

General sensations, 271, 272. 
Germs of disease, 122. 
Glands and blood supply, 134. 

Compound, 133. 

Essentials of, 134. 

Gastric, 173. 

Intestinal, 176. 

Lacrymal, 286. 

Lymphatic, 77, 183. 

Mucous, 169. 

Oil, 130. 

Salivary, 166. 

Simple, 133, 135. 

Sweat, 133. 
Glasses, wearing, 299. 



378 



INDEX. 



Gliding joints, 339. 
Glossopharyngeal nerves, 239. 
Glottis, 170, 171. 
Gluten, 145. 
Glycogen, 178, 202. 
Graham flour, 148. 
Grains, 147. 
Granula, 189. 
Grape sugar, 179. 
Grates as ventilators, 114. 
Gravity and circulation, 61. 
Gray matter of brain, 241. 

Matter, circulation in, 249. 

Matter of spinal cord, 28, 29, 31. 
Gray nerve fibers, 28. 
Gullet, 160, 170, 171, 186. 

Habit, 212. 

Acquired reflex action, 267. 
Hair, 130, 133 ; bulb, 130. 
Hammer bone, 333. 
Hard palate, 170. 
Harmony in muscle action, 21, 36. 
Hauser, Kaspar, 271. 
Haversian canals, 337. 
Hawking, 95. 

Headaches from eyestrain, 299. 
Health, 1. 
Hearing, 304. 
Heart, action of, 45 ; rhythmic, 64. 

Auricles of, 41 , 46. 

Beat of, 39, 49. 

Blood tubes joining, 42. 

Covering, 40. 

Dissection of, 42. 

Muscle, 344. 

Nourishment of, 61. 

Position of, 40. 

Size of, 41. 

Sounds of, 49. 

Structure of, 41. 

Valves of, 41. 

Ventricles of, 41, 46. 

Work and rest of, 48. 
Heat and alcohol, 209. 

Conduction of, 137. 

Convection of, 137. 

Distribution of, 138. 

And exercise, 137. 

From oxidation, 109. 



Heat, production of, 106. 

Radiation of, 137. 

Ways of giving off, 137. 
Heating, direct, 118; indirect, 118. 
Hemispheres of brain, 235, 240. 
Hemoglobin, 74, 104. 
Hemorrhage of lungs, 315. 

Of stomach, 315. 
Hepatic arteries, 177 ; veins, 177, 186. 
Hibernation, 201. 
Hiccuping, 95. 
Hinge joint, 339. 
Hoarseness, 313. 
Hog cholera, bacillus of, 123. 
Hope in illness, 325. 
Hot drink, 191. 
Humerus, 332, 333. 
Humor, aqueous, 288, 289. 

Vitreous, 288, 289. 
Hump, camel's, 201. 
Hunger, 276. 
Hyaloid membrane, 289. 
Hygiene of bones, 339. 

Of breathing, 97. 

Defined, 3. 

Of digestion, 190. 
Hyoid bone, 333. 
Hypoglossal nerve, 240. 

Ice water, 152. 

Ignoring nerve currents, 266. 
Iliac arteries, 44; veins, 44. 
Image, inversion of, 290. 
Immovable joints, 339. 
Importance of retina, 293. 
Impulse, nerve, 28, 36. 

Transmission of, 36. 
Impurities in water, 151. 
Incisor, 164. 
Incus, 333. 
Indestructibility of force, 204. 

Of matter, 203. 
Indirect heating, 118. 
Induction current, 266. 
Inebriety, Clum, 260; Crothers, 260. 

A disease, 253. 

Palmer, 260. 
Inhibition, 67. 
Innominate bones, 333. 
Insertion of muscle, 10, 15. 



INDEX. 



379 



Inspiration, 91 ; and expiration, 92. 

Forces of, 94. 

Resistances to, 94. 
Intelligence, 243 ; and convolutions, 240, 
Interference with reflex action, 35. 
Intervertebral cartilages, 335. 
Intestine, 176, 177. 

Large, 186, 188 ; small, 160, 176, 186. 
Intestinal glands, 176, 179. 
Inversion of image, 290. 
Invertin, 179. 
Iris, 288. 

Iron, in blood, 74. 
Irritant poisons, 323. 
Irritation of eye, 298. 
Ivy poisoning, 324. 

Jacketed stoves, 117. 
Joints, 19, 339. 
Judgment, 266. 
Jugular vein, 44. 
Juice, gastric, 173. 

Intestinal, 179. 

Lime, 150. 

Pancreatic, 177. 

Kaspar Hauser, 271. 
Katabolism, 203. 
Kidneys, 139. 

Diseased, 197. 

And skin, 141, 142. 
Kinds of teeth, 164. 

Labor, physiological division of, 4. 
Lacrymal bone, 333 ; gland, 286. 
Lacteals, 181, 184, 186. 
Lacunae of bone, 337. 
Lamellae, of bone, 337. 
Lamps, in sickroom, 328. 
Larynx, from above, 311. 

Structure of, 310. 
Lateral process, 331. 
Laughing, 95. 
Laxative foods, 189. 
Leather, 132. 
Ledger of body, 195. 
Legumin, 145. 
Lens capsule, 289. 

Crystalline, 288, 289. 



Levers, 16, 17. 

Life, artificial, 1 ; natural, I. 

Processes, 203. 
Ligament, suspensory, 288. 
Ligaments, 19. 
Light, electric, 296. 

In sickroom, 325. 

Strength of, 297. 
Lingering of sensations, 267. 
Live dust, 121. 
Liver, 177, 160. 

As food, 189. 

Position, 85. 

Starch, 178. 
Lobes, olfactory, 237. 
Local sign, 281. 

Location of brain functions, 244. 
Locomotion, 19; by reaction, 2a 
Loss and gain of body, 195. 
Loudness of voice, 311. 
Lumbar vertebras, 332, 333, 335. 
Lung diseases, 126. 
Lungs, 87. 

Parts of, 84. 

Capacity of, 97. 

Dorsal view of, 43. 

Hemorrhage of, 315. 
Lymph, 79. 

Cavities, 80. 

Flow of, 77. 

Importance of, 80. 

Renewal of, 200. 

Spaces, 75. 

Tubes, 76. 

Variations in, 80. 
Lymphatic glands, 77, 183. 
Lymphatics, 183, 184. 

Malar bone, 333. 

Malleus, 333. 

Malted milk, 155. 

Massage, 81. 

Masseter muscle, 8. 

Mastication, imperfect, 192. 

Matter, animal, in bone, 338, 339. 

Indestructibility of, 203. 

Mineral in bone, 338, 339. 
Maxilla, inferior, 333. 

Superior, 333. 
Meals, conversation at, 192, 



38o 



INDEX. 



Meat, 146 ; baking, 1 16 ; boiling, 156 ; 
broiling, 156; roasting, 156 ; salted, 
189; smoked, 189. 
Mechanism, of body, 2. 
Media, refracting of eye, 289. 
Medullary sheath, 27. 
Membrane, hyaloid, 289. 
Memory, 267. 
Meningitis, 248. 
Mesentery, 161, 186. 
Mesenteric artery, 177 ; vein, 186. 
Metabolism, 203. 
Metacarpus, 333, 334. 
Metatarsal bones, 333. 
Metatarsus, 332, 333. 
Middle ear, 305. 
Milk, 144, 146. 

Boiled, 189 ; Malted, 155. 

Souring of, 127. 

Teeth, 164. 
Mind, control of, 247. 
Mineral matter in bone, 338, 339. 
Mitral valve, 41. 
Mixed diet, 153. 

Joints, 339. 
Modification of respiration, 95. 
Molars, 164. 
Molds, 121. 
Morphia, 255. 
Morphine, 255. 
Motion, experiments with, 7. 

Involuntary, 24. 

And locomotion, 19. 

Production of, 106. 

Voluntary, 24. 
Mouth, 162 ; breathing through, 98. 
Movable joints, 339. 
Movements of eye, 287. 

Of respiration, 91. 
Mucous glands, 169 ; Membrane, 86, 87. 
Mucus, 169. 
Muscle, action of, 9. 

Capillaries of, 54. 

Explosion in, no. 

Insertion of, 10, 15. 

Normal condition of, 13. 

Origin of, 10, 15. 

Shortening, 13, 24. 

Structure of, 10, n. 
Muscle-action, harmony in, 36. 



Muscle-action, laws of, 12. 
Muscle-cells, 5, 345 ; of heart, 344. 
Muscle-fiber, a cell, 345. 
Muscle-fibers compared, 344. 

Plain, in artery, 50. 

Plain and striated, 52, 344. 

In lymph tubes, 77. 
Muscle-plasma, coagulation of, 346. 
Muscles, arrangement of, 341. 

Arterial, exercise of, 233. 

Biceps, 8. 

Ciliary, 290, 291. 

Of expression, 345. 

Of eyeball, 286, 288. 

And fat, 346. 

Forms of, 341. 

Importance of, 12. 

Names of, 344. 

Number of, 341. 

Papillary, 46. 

Relation to bone, 15. 

Size of, 341. 

Skeletal, 15. 

Sphincter, 175. 

Superficial, 342, 343. 

Symmetrical development of, 14. 

Temporal, 9. 

Triceps, 8. 
Muscular exertion and urea, 202. 

Power, loss of, 37. 

Sense, 272. 

Sense and sight, 274. 
Myosin, 145. 

Nails, 133. 

Rusty, wounds from, 323. 
Names of muscles, 344. 
Narcosis, 254. 
Narcotics, 254, 257. 
Nasal bones, 333. 
Nature, punishments, 1, 227. 

Of sensation, 264. 
Nausea, 272. 
Near sight, 291, 292. 
Neck, bleeding from, 314. 

Of tooth, 163, 164. 
Negative after-images, 295. 
Nerve cells, 5, 28. 

Centers, 29. 

Currents afferent and efferent, 268, 269. 



INDEX. 



381 



Nerve, currents ignoring, 266. 

Endings, in skin, 278. 

Fibers, crossing of, 35, 243. 

Fibers, destination of, 33. 

Fibers, function of, 28. 

Fibers, gray, 28. 

Fibers, sheath of, 28. 

Fibers, similarity of, 262. 

Fibers, structure of, 27, 28. 

Impulse, 28, 36. 

Roots, functions of, 33. 

Stimuli, 261. 

Supply of heart, 66. 

Supply of tongue, 302. 
Nerves, Auditory, 239, 305. 

Cranial, 237, 242. 

Of diaphragm, 100. 

Effect of pressure, 37. 

Facial, 238. 

Glossopharyngeal, 239. 

Of hearing, 242, 305. 

Of heart, 66. 

Hypoglossal, 240. 

Olfactory, 238, 303. 

Optic, 237, 238, 288. 

Pneumogastric (see vagus). 

Sciatic of frog, 9. 

Of smell, 303. 

Spinal, 26. 

Structure of, 27. 

Of taste, 302, 301. 

Trigeminal, 237. 

Trophic, 251. 

Vagus, 66, 239. 

Vaso-constrictor, 67. 

Vaso-dilator, 67. 

Vaso-motor, 68. 
Nervous impulse, nature of, 28, 36. 
Nervous system and alcohol, 250. 

Cerebro-spinal, 24. 

Sympathetic, 65, 66. 

And telegraph, 268. 
Nervous tissue and starvation, 247. 
Neural arch, 330; ring, 330. 
Neuralgia and cold baths, 233. 
Neuroglia, 241. 
Nicotine, 258. 
Nitrogen in air, 100. 
Nose, bleeding from, 315. 
Nourishment of heart, 61. 



Nucleus, 4; of ciliated cell, 86; 

dermic cell, 53. 
Nurse, qualities of, 325. 
Nursing, 325 ; books on, 328. 
Nutrition, 202. 
Nuts, 191. 

Oats, 149. 

Occipital bone, 332, 333. 

Oculist, consultation of, 299. 

Odontoid process, 335. 

Oil gland, 130. 

Olfactory bulb, 303, 238, 242. 

Lobes, 237, 242. 

Nerves, 303, 242, 238. 
Onions, 189. 
Opium, 255. 

Optic nerves, 237, 242, 288, 297. 
Organ, defined, 3. 
Organs of digestion, 160. 

Ledger account of, 195. 
Origin, of muscle, 10, 15. 
Osmosis, 182. 
Outline of digestion, 187. 
Oxidation, source of heat, 109. 

Of tissues, 107. 
Oxygen in the air, 100. 

Amount used, 104. 

In blood, 104. 

Storage in tissues, no. 
Oxy-hemoglogin, 104. 
Oysters, 189. 

Pain, 274; extent of, 275. 

In eyes, 294. 

A general sense, 276. 
Palate bone, 333. 

Hard, 170, 171. 

Sense of taste in, 302. 

Soft, 160, 170, 171. 
Pancreas, 160, 177, 186. 
Pancreatic duct, 186. 

Juice, 177, 178. 
Panting, 96. 
Papillae, circumvallate, 303. 

Filiform, 301. 

Fungiform, 301. 

Of skin, 130, 131, 279. 

Of tongue, 301. 
Papillary muscles, 46. 



of epi« 



382 



INDEX. 



Parietal bone, 332, 333. 

Parotid salivary gland, 186. 

Pastry, 189. 

Patella, 332, 333. 

Peaches, 189. 

Peas, green, 189. 

Pepper, 189. 

Pepsin, 173. 

Peptone, 176. 

Periosteum, 19. 

Peritoneum, 161. 

Perspiration, 130 ; amount of, 136. 

Insensible, 135; sensible, 135. 
Phalanges, 333, 334. 
Pharynx, 160, 169. 
Physician's directions, 326. 
Physiology defined, 3. 
Pia mater, 235. 
Pie, 191. 

Pigeon without cerebrum, 241. 
Pigment cells, 52, 53. 

Of eye, 288. 

Of human skin, 132. 
Pitch of voice, 312. 
Pivot joint, 339. 

Plain muscle fibers, 49, 50, 344. 
Plants, relation to animals, 205. 
Plasma, 73. 
Pleura, 87. 
Plexus, solar, 66. 
Plums, 189. 
Poison ivy, 324. 
Poisons, 322, 347. 

Irritant, 323 ; neutralizing, 323. 
Pollen, 121. 
Pores, sweat, 130. 
Portal circulation, 177; Vein, 177. 
Positive after-images, 295. 
Postcaval vein, 42, 44, 177, 186. 
Potatoes, 149, 189. 
Potential energy, in respiration, 93. 
Poultry, 189. 
Power, of levers, 16. 
Precaval vein, 42, 44, 186. 
Premolars, 164. 
Preservation of food, 127. 
Pressure sense, 280. 

Effect on nerves, 37 ; on veins, 58. 
Prevention of sneezing, 328. 
Process, articulating, 331 ; lateral, 331. 



Process, odontoid, 335. 

Spinous, 331. 
Processes, of vertebra, 330. 
Production of heat, 106; of sound, 306. 
Pronation, 337. 
Protection of eye, 285. 
Proteid food, 146. 
Proteids, 145 ; importance of, 145. 

Vegetable, 147. 
Protoplasm, 4; animal, 202; vegetal. 202^ 
Ptyalin, 168, 176. 
Puff-balls, 121. 
Pulmonary artery, 42; veins, 42, 43. 

Capillaries, 86. 
Pulp-cavity, 163, 164. 
Pulse, 40. 

Punishment, by nature, 227. 
Pupil, 288, 289. 
Putrefaction, bacteria of, 127. 
Pylorus, 175. 

Quality of voice, 312. 

Quantity of blood in organs, 75. 

Rabbit, muscles of leg, 9. 

Nerves of leg, 9. 
Radiation of heat, 137. 
Radius, 332, 333. 
Rainwater, 150. 
Raspberries, 189. 
Rate of blood-flow, 59. 

Of heart beat, 39. 

Of respiration, 95. 
Reaction of blood, 75. 

Time, 262. 
Reading in convalescence, 298 ; heavy 
books, 296; mornings, 297 ; even- 
ings, 297 ; outdoors, 296. 
Receptacle of chyle, 186. 
Rectum, 188. 

Reference in sensation, 282. 
Reflex action, 30, 32, 263. 

Essentials of, 32. 

And habit, 267. 

Importance of, 32. 

Of spinal cord of frog, 30. 
Refracting media of eye, 289. 
Regulation of blood-flow, 68, 69, 107. 

Of heart beat, 66, 67. 

Of lymph-flow, jj. 



INDEX. 



383 



Regulation of respiration, 99, 108. 

Of temperature, 136. 
Renal arteries, 44; veins, 44. 
Renewal of blood and lymph, 200. 
Rennet, 174. 
Rennin, 174. 

Repose, effect on digestion, 192. 
Reserve air, 97. 
Residual air, 97. 
Respiration, abdominal, 95. 

And candle, 201. 

Chemistry of, 100. 

Control of, 99. 

Forced, 94. 

Modifications of, 95. 

Movements of, 91. 

Organs of, 84. 

And oxidation, 201. 

Rate of, 95. 

Thoracic, 95. 
Respiratory center, 99 ; sounds, 99. 
Rest of brain, 246, 247. 

Of eyes, 297. 

Of heart, 48.- 

Usefulness of, 268. 
Restoring breathing, 320. 
Resuscitation from carbon dioxid, 322. 

From drowning, 317. 
Retina, 287, 292, 293. 
Rhubarb, 189. 

Ribs, 332, 333; in respiration, 92. 
Rice, 149, 189. 
Rickets, 339. 
Rigor mortis, 346. 
Ring, neural, 330. 
River and blood-flow, 195. 
Roasting meat, 156. 
Rods and cones, 293, 292. 
Roots of spinal nerves, 26, 29, 31. 
Running, 20. 
Rye, 149. 

Sacrum, 333, 334, 335. 

Sago, 189. 

Salines, 302. 

Saliva, amount of, 168; uses of, 168. 

Salivary glands, 166, 186. 

Salted meat, 189. 

Salts, 153. 

Satiety, 272. 



Scapula, 332, 333. 
Sciatic nerve of frog, 9. 
Sclerotic coat, 287, 288. 
Sculpture and anatomy, 346. 
Semicircular canals, 305, 306. 
Semilunar valves, 42. 
Sensation centers, 243, 245 

Defined, 265. 

Nature of, 264. 

And stimulus, 262. 
Sensations and brain, 30. 

Of color, 294. 

Common, 272. 

Cutaneous, 278. 

General, 271. 

Lingering, 267. 

Referred to nerve ends, 282. 

Relative, 265. 

Subjective, 263. 
Sense of equilibrium, 306. 

Of hearing, 304. 

Muscular, 272. 

Of sight, 285. 

Of smell, 303. 

Of taste, 301. 

Temperature, 283. 

Of touch, 279. 
Senses, classification of, 271. 
Serous cavities, 80. 
Sewer and water pipes, 199. 
Sheath, medullary, 27. 

Of muscle fiber, n, 12. 

Of nerve fiber, 28. 
Sick, care of, 325 ; food for, 327.. 
Sickroom, 324. 

Sweeping, 125, 327. 

Temperature of, 325. 
Sighing, 95. 
Sight, 285. 

Sigmoid flexure, 188. 
Sign, local, 281. 
Skeleton, 330. 

Appendicular, 330. 

Axial, 330. 

Cavities of, 337. 
Skeleton, side view of, 332. 
Skin, color of, 132. 

Functions of, 130, 136. 

And kidneys, 141. 

Papillae of, 279. 



3§4 



INDEX. 



Skin, structure of, 130. 

Skull, 332, 333. 

Sleeplessness, 246. 

Small intestine, 160. 

Smell, 303. 

Smoked meat, 189. 

Snake bites, 324. 

Sneezing, 95 ; prevention of, 328. 

Sniffing, 95, 304. 

Snoring, 95. 

Sobbing, 95. 

Socket-joint, 339. 

Soft palate, 160. 

Solar plexus, 66. 

Sound, 306. 

Sounds of heart, 49. 

Respiratory, 99. 
Soup, 156 ; value of, 191. 
Special senses, 271, 278. 
Specific gravity of blood, 75. 
Speech center, 245, 264. 

And voice, 312. 
Sphenoid bone, 333. 
Sphincter muscles, 175. 
Spices, 189. 
Spinach, 189. 
Spinal bulb, 236, 245, 246. 
Spinal column, 334; flexibility of, 335. 
Spinal cord, 24. 

Cross section of, 28. 

Figure of, 29. 

Functions of, 29. 

Reflex action of, 30. 
Spinal nerves, 26. 

Roots of, 26, 29. 

Effect of severing, 34. 
Spine, curvature of, 339. 
Spinous process, 331. 
Spirillum, of Asiatic cholera, 123. 
Spitting, 96. 
Spleen, 81. 
Spot, blind, 293. 

Yellow, 288. 
Spots, cold, 283 ; warm, 283. 
Sprains, 339. 
Squash, 189. 
Standing, 19. 
Stapes, 333. 
Starch, 189. 
Starvation of cells, 200. 



Starvation of nervous system, 247. 

Steapsin, 179. 

Stereoscopic vision, 295. 

Sternum, 332, 333. 

Stiffened joints, 340. 

Stimulants, 210, 212 ; in resuscitation, 320. 

Stimulating nerve roots, 34. 

Spinal nerves, 33. 
Stimuli of nerves, 261. 
Stimulus and sensation, 262. 
Stings of bees, 324. 
Stirrup bones, 333. 
Stomach, 160, 172, 186. 

Absorption from, 175. 

Blood-supply of, 173. 

Coats of, 172. 

Churning, 174. 

Digestion, time of, 175. 

Hemorrhage of, 315. 

Position, 85, 160, 172, 186. 

Structure of, 172. 
Storage of oxygen, no. 
Stove, 116; with jacket, 117. 
Strength of light, 297. 

Source of, 14. 
Structure of artery, 51. 

Of bone, 18, 337. 

Of brain, 238, 239, 241. 

Of eye, 288. 

Of gullet, 171. 

Of heart, 41. 

Of kidney, 139, 140. 

Of larynx, 310. 

Of muscle, 10, n. 

Of nerves, 27. 

Of retina, 292. 

Of skin, 130. 
Structure of stomach, 172; of tooth, 163, 

164. 
Subclavian vein, 44, 186. 
Subjective sensations, 265. 
Sublingual salivary gland, 166, 186. 
Submaxillary salivary gland, 166, 186. 
Sucking, 96. 

Suffocation in wells, 322. 
Sugar, 144 ; cane, 179 ; grape, 179. 

In diabetes, 199. 
Sunshine, 139. 
Sunstroke, 317. 
Supination, 337. 



INDEX. 



38S 



Suspensory ligament, 288. 

Swallowing, 171 ; and breathing, 170, 171. 

Sweat, 130. 

Composition of, 135. 

Evaporation of, 137. 

Glands, 130, 133, 135. 

Pores, 130. 
Sweeping, 125. 

SiQkroom, 125, 327. 
Sweetmeats, 191. 
Sweets, where tasted, 302. 
Swimming, 321. 

Sympathetic nervous system, 65, 66. 
Sympathy between eyes, 294. 

In nursing, 325. 
Synovia, 19. 
Systole, 47. 

Table of bones, 333. 

Tapioca, 189. 

Tarsal bones, 333. 

Tarsus, 332, 333. 

Taste, 301. 

Tasting, conditions of, 302. 

Tea, 154, 189, 212; beef, 155. 

Tears, 286. 

Teeth, 162, 163. 

Arrangement of, 164. 

Care of, 166. 

Kinds, 164. 

Milk, 164. 
Temperance drinks, 211. 
Temperature of body, 108. 
Temperature, regulation of, 136. 

Sense, 283. 

Of sickroom, 325. 

Effect on taste, 302. 
Temporal bone, 332, 333 ; muscle, 9. 
Tendinous cords, 41, 46. 
Tendon, 7, 10, 11, 15. 
Tennis, 228. 
Tetanus, 35. 
Thein, 154. 
Theobromin, 155. 
Thermometer in sickroom, 325. 
Thigh, wounds in, 315. 
Thirst, 276, 272. 
Thoracic duct, 183. 

Respiration, 95. 

Vertebra, 331, 335. 



Thorax, cross section of, 89. 

Thorns, wounds from, 323. 

Thyroid cartilage, 309. 

Tibia, 332, 333. 

Tidal air, 97. 

Time for bathing, 233 ; of eating, 193. 

Tissue denned, 3. 

Connective, 11, 12. 

Fatty, 201. 
Tissues, oxidation of, 107. 
Tobacco, 258, 299. 
Tomatoes, 189. 
Tongue, 162. 

Nerves of, 301. 

Papillae of, 301. 
Tooth, structure of, 163, 164. 
Touch, sense of, 279. 

Corpuscles of, 279. 
Trachea, 43, 86. 
Training and alcohol, 209. 
Transfusion of blood, 81. 
Transmission of nerve impulse, 36. 
Treatment of burns, 316. 

Of the drowned, 317. 

Of fainting, 316. 

In poisoning, 322, 347. 
Triceps muscle, 8. 
Tricuspid valve, 41. 
Trigeminal nerve, 237. 
Trophic nerves, 251. 
Trypsin, 178. 
Tube, digestive, 159. 

. Eustachian, 305, 306. 
Tubes, lymph, 76. 
Tuberculosis, bacillus of, 123. 
Turbinated bones, 333. 
Typhoid fever, 151; bacillus of, 123. 

Ulna, 332, 333. 

Upsetting of boats, 321. 

Urea, 139; and muscular exertion, 202, 

Uses of bones, 330. 

Utilization of energy, 205. 

Uvula, 160. 

Vagus nerves, 66, 239. 

Valve, mitral, 41 ; tricuspid, 41. 

Valves of heart, 41. 

Of lymph tubes, 76. 

Semilunar, 42, 46. 



386 



INDEX. 



Valves of veins, 57, 
Variation of blood-supply, 50. 
Vaso-constrictor nerves, 67. 

-dilator nerves, 67. 

-motor nerves, 68. 
Vegetable proteid, 147. 
Vegetables, 149. 
Vegetal protoplasm, 202. 
Vegetarians, 154. 
Veins, 57. 
— Bleeding from, 315. 

Distribution of, 44. 

Flow in, 61. 

Hepatic, 177, 186. 

Iliac, 44. 

Jugular, 44. 

Mesenteric, 186. 

Portal, 177. 

Postcaval, 42, 44, 177, 186. 

Precaval, 42, 44, 186. 

Effect of pressure on, 58. 

Pulmonary, 42, 43. 

Renal, 44. 

Subclavian, 44, 286. 

Valves in, 57. 
Ventilating flues, 115. 
Ventilation, need of, 114. 

Principles of, 115. 
Ventricle, contraction of, 46. 

Dilation of, 47. 

Of heart, 41. 
Vermiform appendix, 187. 
Vertebra, articulations of, 335. 

Parts of, 330. 

Processes of, 330. 
Vertebrae, cervical, 332, 333, 334. 

Lumbar, 335. 

Thoracic, 331, 332, 333, 335. 
Vesicles, air, 84. 
Villi, 179, 181, 184, 185. 
Vision, stereoscopic, 295. 
Visual center, 264. 
Vital capacity, 97. 
Vitreous humor, 288, 289. 
Vocal cords, 309. 
Voice, 309. 

Change of, 313. 

Culture of, 313. 

Loudness of, 311. 

Pitch of, 312. 



Voice, quality of, 312. 

And speech, 312. 
Volition, 242, 243. 
Voluntary inhibition, 35. 
Vomer, 333. 
Vowels and consonants, 312. 



Walking, 20; in sickroom, 327. 
Warm baths, 233. 

Spots, 283. 
Watching in sickroom, 326. 
Water, 130. 

Boiling, 152. 

Drinking, 152. 

Ice, 152. 

Impurities in, 151, 

Rain, 150. 

Well, 150. 
Water-cushion of brain, 248. 
Water-pipes and bloodstream, 199. 

And sewer, 199. 
Wearing glasses, 299. 
Web of frog's foot, 52, 53. 
Weight of bones, 337. 

In levers, 16. 
Well-water, 150. 
Wheat, 148. 

Flour, 148. 
Whispering, 313 ; in sickroom, 327. 
Whistling, 96. 
White matter of brain, 241. 

Circulation in, 249. 

Of spinal cord, 28, 29. 
Wild game, 189. 
Wind, 116. 

Windows, double, 119. 
Windpipe, 86. 
Work of blood, 39. 

Brain, 246. 

Of heart, 48. 
Worker, outdoor, 2. 

Wounds from rusty nails, 323; from 
thorns, 323. 

In thigh, 315. 



Yawning, 95. 
Yeast, 121, 208. 
Yellow spot, 288. 



PHYSIOLOGY 



PRACTICAL AND DESCRIPTIVE 



BY 



BUEL P. COLTON, A.M. 

PROFESSOR OF BIOLOGICAL SCIENCES 

ILLINOIS STATE NORMAL UNIVERSITY 

AUTHOR OF 

"PHYSIOLOGY, EXPERIMENTAL AND DESCRIPTIVE" 

"PHYSIOLOGY, ILLUSTRATED BY EXPERIMENT" 

"ELEMENTARY PHYSIOLOGY AND HYGIENE" 

"ZOOLOGY, DESCRIPTIVE AND PRACTICAL" 

"TEACHER'S MANUAL OF ZOOLOGY" 

"PRACTICAL ZOOLOGY" 



PART II — PRACTICAL 



D. C. HEATH & CO., PUBLISHERS 
1906 



COLTON'S PHYSIOLOGIES 



PHYSIOLOGY : Experimental and Descriptive . . . $1.12 
For Normal Schools and Colleges. 440 pages. Illus- 
trated in colors. 

PHYSIOLOGY: Briefer Course 90 

For High Schools. 399 pages. Illustrated in colors. 

PRACTICAL PHYSIOLOGY 60 

Laboratory Work in Physiology. 168 pages. Illustrated. 

PHYSIOLOGY: Practical and Descriptive . . . 1.40 

This consists of the Briefer Course and the Practical Physi- 
ology bound in one volume. 

ELEMENTARY PHYSIOLOGY AND HYGIENE . .60 

For Grammar Schools. 320 pages. Illustrated. 

GOOD HEALTH FOR GIRLS AND BOYS ... .45 

An Introduction to the Elementary Physiology, for Inter- 
mediate Grades, by Bertha M. Brown. 164 pages. 
Illustrated. 



D. C. HEATH & CO., Publishers, Boston, New York, Chicago 



Practical. 



Copyright, 1906, 
By BUEL P. COLTON. 



PREFACE 

We remember what we do. We remember what we see. But 
we often forget what we are told, and much that we read slips 
away from memory. These solid facts are the foundation of 
this book and justify its existence. In the study of material 
objects it is now everywhere recognized that the student must 
see, handle, and get first-hand knowledge of the subject-matter. 
No good teacher tries to teach botany or zoology without plac- 
ing specimens in the hands of the students. In physics and 
chemistry the laboratory is an acknowledged necessity. W 7 hy 
not for physiology ? The human body is the most complicated 
of the products of nature. It is absurd to assume that we can 
understand its mechanism and operations by mere reading, no 
matter how well illustrated the text-book may be. Many years 
ago, when the writer began teaching physiology, he took it for 
granted that students would understand what they read, without 
seeing the things themselves. The writer had, for his own 
reading, Huxley's " Elementary Lessons in Physiology." Now 
Huxley was not only master of his subject, but a master of the 
English language ; so much so that selections from his writings 
are to be found in many of the standard works on English litera- 
ture. Huxley's description of the heart is unusually good and 
the illustrations excellent. But on one notable day the writer 
ventured to dissect a heart. It was a revelation. He found he 
had no real conception of its structure and workings. This one 
fact led to his pedagogical conversion. Foster, in his " Primer 
of Physiology," says, " Did you ever look through a good micro- 
scope at the thin, transparent web of a frog's foot, and watch the 
red blood coursing along its narrow channels ? If not, go and 



iv PREFACE 

look at it at once ; you will never understand any physiology 
till you have done so." 

It is unfortunate that physiology comes earlier in the course 
than physics and chemistry. Logically it should follow them, 
as it is a higher science. A knowledge of many of the princi- 
ples of physics and chemistry is essential to an understanding 
of the workings of the body, whereas a knowledge of physiology 
is not involved in approaching the physical sciences. At least 
two considerations have had much to do in determining the 
existing relations of these studies. First, since some famil- 
iarity with higher mathematics is required, physics is usually 
placed late in the course. Second, on account of the desira- 
bility of having as many students as possible learn something 
of hygiene, physiology is placed earlier in the course. What- 
ever the explanation, the fact stands that if a student tries to 
solve the problems of physiology, with no previous study of the 
principles of physics and chemistry, he finds himself badly 
handicapped. Even if the teacher tries to explain levers, air 
pressure, solution, valve action, etc., he labors at a disadvantage. 
Clear concepts cannot be built up in a day ; they are a matter 
of growth. Only by a series of experiments, beginning with the 
simplest, can the student be well prepared to apply physical 
laws to their operation in the living body. The hopeful feature 
of the situation is that the better schools are introducing the 
elements of physics and chemistry all through the grades, so 
that in a few years most students will be prepared to begin 
physiology by having a stock of ideas on such subjects as air 
pressure, potential energy, oxidation, etc. 

The writer is aware that in many schools the conditions and the 
traditions are not the most favorable to ideal work. The teacher 
is urged to keep in mind that the more of the work the students 
themselves do, the more they learn. Hence it is desirable to 
have as much classroom and home work as possible and not to 
resort to demonstration more than is necessary. But of course 
the work must be varied to suit the circumstances. 



PREFACE v 

These directions have been in use for years and many of them 
have been repeatedly corrected. Still, the author does not con- 
sider them perfect, and will consider it a favor if teachers who 
use them will call his attention to parts that are not clear to the 
student, or that, for any reason, are not " workable." 

The manuscript has been critically read by Dr. W. S. Hall, 
Professor of Physiology, Northwestern University Medical 
School, Chicago. It has also been read by Professor F. D. 
Barber, Illinois State Normal University, who has given valu- 
able suggestions as to the physical and chemical experiments. 
Dr. Casey Wood, of Chicago, has read the proof of the chapters 
on the eye. To these gentlemen the author expresses his heart- 
felt thanks. The author also wishes to thank the Spencer 
Lens Company for kindly furnishing the full-page cut of the 
microscope. 



CONTENTS. 

PAGE 

Introduction — To the Teacher ix 

CHAPTER 

I. The Use and Care of the Microscope — 

Cells ...... . i 

II. Muscles 4 

III. The Spinal Cord and Spinal Nerves . 15 

IV. Structure and Action of the Heart . 21 
V. Structure and Action of the Blood Tubes 32 

VI. The Blood . 43 

VII. Respiration ....... 47 

VIII. Ventilation and Heating .... 59 

IX. Excretion ....... 63 

X. Foods 69 

XI. The Digestive System ..... 79 
XII. Action of the Digestive Liquids — Absorp- 
tion ........ 92 

XIII. The Brain 98 

XIV. Touch, Taste, Smell . . . . .102 
XV. External Features and Structure of the 

Eye ........ 105 

XVI. The Action of the Eye . . . .111 

XVII. The Ear 118 

XVIII. The Voice 122 

XIX. The Skeleton 127 

XX. Yeast and Bacteria . . . . 133 

Appendix ......... 141 

Index .......... 147 



INTRODUCTION. 

TO THE TEACHER. 

The Physiology Room. — For the physiology work the room 
should be well lighted, preferably facing north. The windows 
ought to extend to the ceiling. If the room is on the upper floor, 
skylights may give added light. The ventilation should be first- 
class. 

Tables. — Two students can work together advantageously, and 
will need a table two feet wide, four and a half feet long, and 
twenty-nine inches high. There should be two drawers, provided 
with locks, for dissecting sets, notebooks, etc. Arrange the tables 
so as to give the students the best light possible. 

Water Supply. — There should be an ample supply of hot and 
cold water. It is better to have two or three sinks in a large room 
and for a large class, as it saves time. There should be a roller 
towel at each sink, with soap, soap dishes, and nail brushes (the 
cheap wooden-back brushes serve very well) . If there is no water 
supply, a tank with faucet will serve, with large pails of galvanized 
iron for the waste water. For washing, a shallow wooden trough, 
lined with zinc, may be used. This should have a faucet, or spout 
and plug, at one end. 

Dissecting Sets. — Each student should have a scalpel, cartilage 
knife, scissors, blowpipe, forceps, and dissecting needle in a neat, 
light case. Such sets are put up by The Bausch and Lomb Optical 
Co., Rochester, N.Y., and by the Spencer Lens Co., Buffalo, 
N.Y. Avoid cheap sets, especially those containing weak 
tweezers instead of good forceps that will grip firmly at the tip. 
In addition to the above, the teacher should have a pair of 



x INTRODUCTION. 

medium-sized bone forceps, a pair of fine scissors, clamps (bull- 
dog forceps), watchmaker's glass, aluminum probe, etc. For in- 
jecting, the teacher should have a good brass syringe, with a set 
of nozzles of various sizes. 

Supervision of Dissection. — i . The student should follow the 
printed directions carefully. He should read the sentence through 
before beginning any operation. He should not cut anything 
without directions, and should always know what he is cutting. 
2. Most of the cutting is to be done with the scissors, not with 
the scalpel. 3. When he does use the scalpel, he should use the 
handle more than the blade. 4. The left hand should be in con- 
stant use with the forceps, holding and steadying the parts under 
examination. 5. The forceps should be held like a pen, not like 
tongs. 6. Organs should not be touched with a sharp point, 
unless direction is given for so doing. 7. When an organ is to 
be lifted or pushed aside, the' forceps, the handle of the scalpel, 
or the fingers should be used. Even the finger nails may tear the 
liver. 

Demonstrations. — The teacher should make many dissections 
for demonstration of points too difficult for the student to work 
out for himself. In many cases, too, the student has not the time 
to make all the dissections that he ought to see. Some of the 
more advanced students, or those who have more time, should 
prepare some of this material, and thus benefit themselves and 
assist the teacher. 

Dissecting Boards, Paper, etc. — There should be a dissecting 
board for each two students, eighteen inches'long and twelve inches 
wide, of inch pine, dressed. In use, this should be covered with 
paper, which may be held in place by tacks. For dissecting the eye, 
use a piece of pine three-sixteenths of an inch thick, six inches wide, 
and eight inches long. Have a good supply of straw paper. For 
many dissections the boards are not needed. In dissecting the 
heart and lungs, use two or more thicknesses of paper. Hammer and 
small nails will be needed in tacking out rabbits. Special supports 
for the dissection of the brain and spinal cord are described later. 



INTRODUCTION. xi 

Disposal of Refuse. — Before starting to carry refuse and soiled 
paper to the waste pail, be careful to fold the paper in from all 
sides. 

Frogs. — There can be no good physiology teaching without 
frogs. They are necessary for showing the action of muscle and 
nerve, reflex action of the spinal cord, the action of the heart, and 
the circulation of blood. Get a good supply early. They are 
easily kept through the winter in a tank of water in the basement. 
They do not need to be fed in the winter, as at this time they 
naturally hibernate. Bullfrogs are best for showing the action of 
muscle, but full-grown grass frogs or leopard frogs serve very well. 
For showing the circulation, the smaller and paler frogs are better. 
During the fishing season, medium-sized frogs can often be ob- 
tained from dealers in sporting goods. A list of dealers in frogs 
is given in the Appendix. 

Preparation for Dissection. — See that the material is on hand 
in time, the day beforehand if it can conveniently be kept in good 
condition. On the day before the students dissect, show them 
some of the more difficult parts of the work. Before they dissect 
the eye, for example, the teacher should go through all the opera- 
tions, calling attention to the points where they might make mis- 
takes. Have the students read over beforehand (not learn) the 
directions for dissection. Tell them beforehand to get their dis- 
secting instruments out and their books open at the right place 
as soon as they take their seats. If they work by twos, or in larger 
groups, have the arrangement agreed on beforehand. Before the 
class enters the room, place the material on sheets of straw paper 
on the tables, so they will lose no time in beginning work. If 
material is to be kept over till the next day, it may be wrapped in 
paper, with the dissector's name on it, and kept in large galvanized 
iron trays. It may be necessary to keep it in formalin (see p. 145) . 

Getting Material for Dissecting. — Considerable of this mate- 
rial is to be obtained from local butchers. The teacher cannot 
take too much care in telling just what is wanted, in what condi- 
tion, and when it is to be delivered. Suppose the teacher wishes 



xn INTRODUCTION. 

a pluck (heart and lungs). He orders it at the butcher's and it is 
promised him. But the ordinary butcher does not kill animals 
every day — be beforehand. Again, the butcher has promised the 
pluck and has, perhaps, told the man who does the killing. But 
this man forgets ; it is out of the usual line to save the lungs. If 
he does not forget, he may think it is too much trouble — what is 
it to him? To get the pluck out in good condition means taking 
more time and trouble than usual. It pays to see this man and 
make it an object to him to get what is wanted and in proper con- 
dition. Little he cares for good methods of teaching, but he 
knows the shine of silver. After all possible care and forethought, 
the teacher will have some disappointments. 

Amount of Material Required. — This depends on whether the 
work is demonstration or class work. The students ought surely 
to dissect the heart and lungs, and have one pluck for each two 
students. Each student should have an eye to dissect. The 
same rabbit can be used for dissecting the spinal cord and the 
hind legs — count one rabbit for each four students and one pair 
of bone forceps for each four. Later, in groups of four, they 
should dissect the organs of the chest and abdominal cavities. 
So, for the best results, the teacher should expect to get one 
rabbit for each two students, for the term's work, with several 
extra for demonstration. If students work on frogs, count one 
frog for each two students, or better, one apiece. If frogs are 
used for demonstration only, it is safe to have six for each class, 
as some may die. The teacher should make plans early as to 
these points. 

Manikin, Skeleton, etc. — A good manikin is very helpful. If 
the school cannot afford one ($200 to $300), plaster of Paris 
models of the separate parts, such as an arm, the brain, the heart 
and lungs, etc., can be bought at from $3 to $10, and serve very 
well. A good human skeleton should be kept in the class room 
and referred to frequently to show the relation of parts, such as 
the position of the brain, spinal cord, diaphragm, etc. ; but there 
is little benefit to the ordinary student in learning the names of all 



INTRODUCTION. xin 

the bones, and he does not need to know how many there are any 
more than he needs to know how many muscles or arteries there 
are in the body. Manikins, models, and skeletons may be bought 
of Ward's Natural Science Establishment, Rochester, N.Y. 

Simple, Home-made Models. — By following the directions, the 
teacher can readily make simple models illustrating the structure 
of the lung, the kidney, a sweat gland, etc. Such models will last 
many years, although the parts made of rubber will need to be 
renewed occasionally. 

Models vs. Dissections. — If the school is well supplied with 
models, the class can get along with less dissection. But models 
can never entirely take the place of dissection. Most models are 
rigid, inflexible, and inelastic ; but pliability and elasticity are the 
chief characteristics of some parts of the body. No model has 
yet been devised which shows well the action of the valves of the 
heart. The general plan of the action of the diaphragm and lungs 
may be shown by apparatus described in the book ; but still it is 
very essential that the students see the diaphragm and the inflation 
of the lungs themselves. 

Reading. — It is desirable to have the student read a few books 
on hygiene, and write a brief summary of each on the permanent 
note paper. The sum and substance of such books as Dr. Prud- 
den's " Bacteria " can be given in from four to six pages of written 
notes. If there is time enough, each student should thus read 
and write a review of one book on each of these subjects : bac- 
teria, food and cooking, exercise, ventilation, emergencies and 
how to treat them. It is not necessary that all the students be 
reading on the same subject at the same time. By a system of 
rotation, ten books on each of these subjects will keep busy a class 
of fifty. A list of such books is given in the Appendix. 

Temporary Notes. — The student should keep notes of all the 
experiments and dissections he makes, and of all that is shown 
him. For class room notes, use a pad of unruled paper, about six 
inches long and four inches wide. Write on but one side of the 
paper. Remove the sheets as they are filled, and keep them in an 



xiv INTRODUCTION. 

envelope open at one end. The envelope should be half an inch 
wider and an inch shorter than the sheets. As the work pro- 
gresses, use an envelope for each subdivision of the subject, label- 
ing each envelope. 

Permanent Notes. — The permanent notes should be written 
with ink on sized paper ten inches long by eight inches wide. 
The paper should be ruled on both sides, with a ruled marginal 
line an inch from one edge. This margin should be perforated 
for binding. For drawings, use a good unruled paper of the same 
size, with the same marginal line and perforations. Pads of these 
two kinds of paper, with labeled covers, are sold by school-supply 
dealers. This system allows any desired arrangement of the notes 
and drawings, irrespective of the time when they were made. If 
the papers are handed in separately, as is often very convenient, 
the student should write his name on the ruled margin. 

Colored Drawings. — It is often desirable to represent organs in 
colors. For this work, use colored inks or water colors. The 
crayon pencils are not good. Represent arteries in red ; veins in 
blue ; the digestive tube, green ; liver, brown ; kidneys, purple ; 
lungs, pink; nervous system, yellow. There should be a box of 
colored crayons for blackboard work, both by teacher and students. 

Laboratory Period. — It is best, when possible, to arrange the 
work so that there will be a double period for laboratory work. 
If the regular recitation period is forty-five minutes, the double 
period, or ninety minutes, will give time to complete many dis- 
sections that otherwise would have to be kept over till another 
day. It is inconvenient to keep such material, even if it is not 
likely to decay. It may be possible to get a double period in 
the afternoon twice a week, in addition to the regular recitation 
period. If the regular recitation period is used for laboratory 
work, the teacher will need to plan the work with special care. 

Economy of Dissecting Material. — If necessary, the same rabbit 
may be used (i) for the dissection of the organs of digestion, p. 79 ; 
(2) for the inflation of the lungs, p. 51 ; (3) for the dissection of 
the spinal cord, p. 15 ; (4) for the study of muscles, p. 7. A frog 



INTRODUCTION. XV 

may be used (i) for showing circulation, p. 34 ; (2) for reflex 
action, p. 20 ; (3) for muscle action, p. 9 ; (4) for the action of the 
heart, p. 29. But the sequence of the book is better since it takes 
into consideration the higher economy — time and energy. 

Filling out Tooth Blanks. — Make mimeograph copies of the 
tooth blank, p. %%. After careful explanation, have each pupil fill 
out the blank. Keep these records, and after a few years make 
out averages, classifying according to age. 

Defects in Sight and Hearing. — Watch closely each pupil to 
detect any defects in sight or hearing. Such defects often exist, 
unknown to the pupil or his parents, and may be the cause of poor 
work. By calling the attention of parents to such defects, medical 
treatment may be secured and the trouble may be remedied. It 
may be desirable to change the pupil's seat to enable him to see or 
hear better. 



-Ocular 



■Drawfcubfc. 



Rack& Rmon> 
Coarse Adjustment 




—Ho rs9> Shoe Baa a, 



Fig. 1. The Microscope and its Parts. 



PHYSIOLOGY: PRACTICAL 
AND DESCRIPTIVE. 

PART II. — PRACTICAL. 

CHAPTER I. 

THE USE AND CARE OF THE MICROSCOPE. CELLS. 

General Rules. — i. Do not touch the lenses, nor allow them 
to touch anything. 

2. Keep the microscope away from dust. 

3. If dust gets on a lens, blow off as much as you can and then 
wipe with chamois skin, or clean, soft cloth, such as old linen. 
Handle the microscope by the pillar below the stage. 

Setting up the Microscope. — The eyepiece should slip easily 
into place by its own weight. To attach an objective, first run the 
tube up by the coarse adjustment, till the lower end of the tube is 
two or three inches above the stage. Then hold the objective 
with the thumb and finger of one hand while the other hand screws 
it to place. See that the threads catch fairly ; do not use force, or 
you may ruin the threads. Take care not to touch the lens. 

Use of a Low-power Objective. — Place on the stage a slide 
holding a mounted object. Slip the ends of the slide under the 
clips. Place the specimen over the center of the hole in the stage. 
Turn the mirror so that it throws light through the hole upon the 
mounted object. Lower your head to the level of the stage and 

1 



2 PHYSIOLOGY. 

watch, while running the tube down by the coarse adjustment ; 
stop when the objective is a quarter of an inch from the glass slide. 
Take hold of the milled head of the coarse adjustment; look 
through the eyepiece and slowly raise the tube until you see the 
object distinctly. Move the slide till the object, or that part of it 
which you wish to examine, is in the center of the field of view. 
Now use the fine adjustment. Never turn the milled head of the 
fine adjustment more than two or three turns in either direction. 

Use of a High-power Objective. — Begin as with the use of 
a low-power objective. Lower the tube until the objective almost 
touches the cover glass, watching closely with your head down on 
a level with the stage. Look through the eyepiece ; by means of 
the coarse adjustment slowly raise the tube till the object comes 
into view. Then use the fine adjustment till the outlines become 
sharp and distinct. Be very careful not to run the objective against 
the cover glass. If you do this, you may ruin the preparation and 
injure the lens. 

The Diaphragm. — Use an opening in the diaphragm of about 
the same size as the front lens of the objective you are using. 

Use of the Eyes. — Always keep both eyes open when using 
the microscope. This may be a little confusing at first, but you 
will soon learn to ignore what you see with the eye which is not 
directed through the microscope. 

Examination of Cells from the Human Body. — i. Epithe- 
lial cells from the inside of the cheek. With the blade of a very 
dull knife, or the handle of a scalpel, gently scrape the inside of 
the cheek. Place a little of the white scraping on a slide in a drop 
of water. Cover with a cover slip and examine under a one-sixth- 
inch objective. The cells are faint, but should show a fine, clear 
outline. In many of the cells the nucleus should be seen. Com- 
pare these cells with Fig. i, Part I. 



THE MICROSCOPE. CELLS. 3 

2. Liver cells. Place on the stage a prepared slide with a sec- 
tion of liver and examine under the one-sixth-inch objective. The 
cells should show distinctly. 

3. In the same way examine slides with sections of skin, spinal 
cord, etc., to see the cells of which all the tissues of the body are 
composed. 

For the parts of the microscope, see Fig. 1, facing page 1. 

Read Practical Methods in Microscopy, Clark (D. C. Heath & Co.). 



CHAPTER II. 

MUSCLES. 

EXPERIMENTS WITH THE MUSCLES IN OUR OWN BODIES. 

i. Clasp the front of the right upper arm. Draw up the fore- 
arm strongly and as far as possible. Note what changes are felt 
in the biceps muscle. 

2. Repeat the experiment, and with the thumb and finger feel 
the cord, or tendon, at the lower end of the muscle, just within the 
angle of the elbow. With what does this tendon connect below? 

3. Place a weight in the hand and repeat the action, noting the 
condition of the muscle during the experiment. Also note the 
condition of the tendon. 

4. Span the muscle, placing the tips of the fingers in the angle 
of the elbow and the tip of the thumb as far as you can up the 
arm. Again bend the arm. What change in the muscle does this 
show? Can you find the upper end, or origin, of the biceps? 
Any muscle that bends a limb, as does the biceps, is called a flexor 
muscle. 

5. Clasp the back of the right upper arm. Forcibly straighten 
the arm. The muscle along the back of the arm is the triceps 
muscle. It is called an extensor because it extends the arm. 
What change takes place in it during the straightening of the arm ? 
Can you find where and how the triceps is connected with the 
forearm ? 

6. Hold the arm rigidly bent at a right angle at the elbow, as 
though to resist some one who attempts either to bend or straighten 
the arm. What is the condition of the biceps and the triceps dur- 
ing this effort ? Clasp the upper arm so as to feel both the biceps 
and the triceps. While doing so bend and straighten the arm, at 

4 



MUSCLES. 5 

first gently, then forcibly, and again with the muscles tense as if to 
resist an effort on the part of some one else either to bend or to 
straighten the arm. What do you learn as to the actions of these 
muscles? Can you tell which is the larger? Can you determine 
which is stronger? 

7. With a tape measure get the circumference of the upper 
arm when the hand hangs by the side. Measure again when the 
forearm is drawn up as strongly as possible. Record the results. 

8. Make a narrow band of paper that snugly fits the middle of 
the upper arm when the hand hangs, freely. Now draw up the 
forearm as strongly as possible. 

9. Clasp the upper side of the right forearm. Clench the right 
hand quickly and forcibly. Repeat rapidly. What changes do 
you feel and see ? Are these muscles flexors or extensors? Trace 
the tendons on the inner surface of the wrist. 

10. Clasp the outside of the forearm just beyond the elbow. 
Straighten the fingers forcibly. What change in the muscles? 
Trace the tendons of the extensors on the back of the hand, while 
repeatedly flexing and extending the fingers. Which are stronger, 
the flexors or extensors? Are the fingers equally free in their 
movements? Are any of their tendons united? 

11. Repeat Experiments 7 and 8 with the thickest part of the 
forearm. 

12. Notice the thick mass of muscle at the base of the thumb. 
Pinch the thumb and forefinger strongly together. What changes 
can be seen and felt? Can you discover the muscles or tendons 
which draw the thumb outward? 

13. Place the hand on the outside of the shoulder. Raise the 
arm to the horizontal. Repeat with a weight in the hand. Note 
the bulging and hardening of the deltoid muscle. 

14. Place the tips of the fingers on the side of the chest just in 
front of and above the armpit. Holding the arm rigid, swing it 
strongly forward. Note the pull given by the pectoral muscle. 
Can you locate the muscle that pulls the arm downward and 
backward ? 



6 PHYSIOLOGY. 

15. Stand erect with the heels close to each other but not quite 
touching. Let the arms hang freely by the sides. Rise on tip- 
toes, without moving otherwise. Repeat ten times. Take hold 
of the calf muscle while rising. What change takes place in the 
muscle ? 

16. Place the hand on the outer and front part of the shin 
while bending the foot upward. Again bend the foot up, this time 
feeling the tendons above the instep. Clasp the leg a few inches 
above the ankle, while bending the foot up and down. 

17. Place the tips of the fingers on the angles of the lower jaw. 
Shut the teeth firmly and note the bulging of the masseter muscles. 

18. Press the fingers on the temples. Again shut the jaw firmly 
and feel the action of the temporal muscles. 

19. Place the hand on the front of the neck a little to one side. 
Bend the head strongly forward. Do you find any muscle that is 
in action? Repeat with the other side. Bend the head forward 
to right and left alternately. 

20. Find the muscles that pull the head back. 

By these experiments we learn that when a muscle works it be- 
comes shorter, thicker, and harder. The shortening is the most 
important act, but usually the hardening and thickening are more 
noticeable. If, then, we wish to find the muscle, or muscles, that 
produce any motion, we should feel about for some bulging and 
hardening of muscle. 

There is another guiding principle in seeking the muscle that 
causes any given motion. The muscles that move the arm as 
a whole are on the body or on the shoulder. The muscles that 
move the forearm are on the upper arm. The muscles that move 
the hand are on the forearm. What is the reason for this arrange- 
ment ? Following this plan of arrangement, with the above test 
of muscle action, we can locate many of the muscles that we so 
often use. 

Which are stronger, over the body generally, the flexors or the 
extensors ? 



MUSCLES. 7 

DISSECTION OF THE HIND LEG OF A RABBIT. 

Material. — A rabbit for each student. If necessary, two or even four 
students may use the^ame specimen, two working on each hind limb. 

This dissection is intended to show the form, parts, external ap- 
pearance, and gross structure of voluntary muscles; also their 
relations to the nerves and to the bones. The joints also are 
studied. The skin should be removed just before the dissection. 

i . In the hind limb of a rabbit observe the heel cord or tendon 
of Achilles, passing upward from the heel along the back of the 
leg. The tendon is the end of the calf muscle, which lies on the 
back of the shin bone. Trace this muscle toward the body and 
note that it passes between two large, flattish muscles, one on the 
inner, the other on the outer back part of the thigh. Separate 
these two fiat muscles, using mainly the handle of the scalpel. 
Remove any fat that is in the way. 

2. Deeply embedded between these muscles is a white cord, 
the sciatic nerve. Trace this toward the body, cutting away any 
muscles or other soft tissues that cover it. How far can you trace 
it? Now follow the nerve outward. Is it of the same size 
throughout? What are its relations to the muscles? 

3. With the scissors cut away the outer of the two flat muscles 
and entirely remove it. Cut away the lower attachment of the 
inner flat muscle. This should leave the calf muscle well exposed 
to view. Loosen the muscle from the shin bone by pushing the 
handle of the scalpel between the two. In separating muscles 
from each other and from the bones, first cut the connective tissue 
between them with the scissors, then separate the muscles with 
the scalpel handle. Try to avoid cutting through the muscle 
sheath into the muscle itself. 

4. The thickest part of the calf muscle is called the belly of the 
muscle. The end by which its tendon is attached to the heel 
bone is the insertion. The other end, less movable, is the origin. 
From what bone, or bones, does it arise, and by how many 
tendons? 



8 PHYSIOLOGY. 

5. Cut across the belly of the muscle, and study its structure. 
The glistening cover is the muscle sheath. Observe that the 
muscle is made up of sections, each of which has its own sheath. 
Note also that the tendons at the end of the muscle are continuous 
with the muscle sheath and with the partitions running through 
the muscle. These partitions are made up of the sheaths of the 
muscle bundles which make up the muscle. Trace the upper part 
of the muscle to find how and where it arises. Then cut away 
this part of the muscle close to the bone, taking with it the adja- 
cent part of the sciatic nerve. 

6. Take hold of the lower part of the muscle and pull toward 
the body. This straightens, or extends, the foot. The calf muscle 
is therefore called an extensor muscle. 

7. With the handle of the scalpel loosen the muscle on the 
front of the shin bone. Prove that its action is to bend, or flex, 
the foot. It is a flexor muscle. Find its origin and insertion. 

8. Rest the knee on a firm support, with the shin bone extend- 
ing upward, or have some one hold it. Take hold of the tendons 
of the calf muscle and the flexor muscle and pull alternately, till 
the relations of the two motions are clear. 

9. Observe the large extensor muscle on the front of the thigh. 
Note that its tendon runs over the knee joint and is inserted at the 
upper end of the shin bone or tibia. In this tendon find a small 
bone ; this is the kneepan or patella. 

10. Loosen the muscle an inch or so above the knee joint and 
cut square across it. Take hold of the lower end and turn the 
tendon downward to expose the knee joint. Observe in the joint 
a very small amount of liquid resembling white of egg. It is 
synovia that lubricates the joint. 

n. Pull the muscle to show that it is an extensor. Note how 
the patella glides in the groove in the lower end of the thigh bone, 
or femur. 

12. On the sides of the joint find the white cords, resembling 
tendons, which hold the thigh bone and the shin bone together. 
These are the ligaments. 



MUSCLES. 9 

13. Sever these ligaments and find other ligaments within the 
joint. Study their connections and uses. The knee joint is a 
hinge joint. 

14. In the same way study the ankle joint. 

15. Clear away the muscles around the hip joint. Cut into it 
and study it carefully. It is a ball-and-socket joint. 

16. Observe the thin layer of gristle, or cartilage, over the ends 
of the bones. Feel of it. Cut off a thin slice of it. What are its 
chief properties and what are its uses? 

17. Thoroughly clean the femur and tibia. Note that each has 
a thin, tough, closely adhering covering, the periosteum. 

18. Where are these bones widest? Where are they narrowest? 
Where are the muscles widest? Where narrowest? What reasons 
for these relations ? 

THE ACTION OF MUSCLE. 

Material. — Live frogs, large ones preferred. Normal salt solution, pre- 
pared by dissolving 6 grams of common salt in 1 liter of distilled water. Re- 
tort stand, with clamp. Small wire hook. 

i. Kill a frog thus : Into a fruit jar of water put a teaspoonful 
of ether, immerse the frog in it, and cap the jar. As soon as the 
frog is motionless cut off its head and run a wire down the cavity 
of the spinal column to destroy the spinal cord. Cut through the 
skin around the base of one of the thighs and strip off the skin 
from the whole of the limb. 

2. Examine more thoroughly the calf muscle ; the end by which 
it is attached below is its insertion, and the upper attachment is 
its origin. 

3. Sever the limb from the body at the hip joint. Separate the 
muscles along the outer back part of the thigh and find the white, 
threadlike sciatic nerve. The nerve must be handled with great 
care ; it must not be pinched nor pulled. Carefully separate it 
from the surrounding muscles and turn it down upon the calf 
muscle. 

4. Cut away all the muscles of the thigh, being careful not to 



io PHYSIOLOGY. 

touch the nerve where it runs down by the knee. Sever the heel 
cord below the heel and separate the calf muscle from the rest of 
the leg, leaving undisturbed its attachment above ; just below the 
knee cut away the shin bone with all the muscles of the leg except 
the calf muscle. 

5. There should now remain the thigh bone with the sciatic 
nerve running to the calf muscle suspended below. Fasten the 
thigh bone to some support, such as a clamp on a retort stand. 
Attach a small hook to the tendon and suspend from it a slight 
weight, for instance a small key. Such a preparation is called a 
nerve-muscle preparation. It should frequently be moistened with 
normal salt solution. 

6. Now take a sharp pair of scissors and snip off the shortest 
possible portion of the upper end of the sciatic nerve. If the 
muscle is closely watched at the time when the nerve is cut, it will 
be seen to shorten, and to lift the weight. 

7. This experiment should be repeated, varying the weight, 
until it is made very clear that when the nerve is stimulated the 
muscle shortens. This is the most important fact about its action ; 
but at the same time it becomes thicker. 

8. Hold the thickest part of the muscle between the thumb and 
finger. Again cut the end of the nerve. Note that the muscle 
becomes harder. 

THE GROSS STRUCTURE OF MUSCLE. 

• Material. — Chipped beef. Corned beef. Fresh round steak. Red 
cord. White tissue paper. 

i. Examine pieces of chipped beef. The red areas are cross 
sections of the bundles of muscle fibers. The white network is 
connective tissue, which forms the sheaths of the muscle and of 
the bundles of muscle fibers. 

2. Examine a piece of lean corned beef. Pick it to pieces and 
trace the bundles of muscle fibers. Note the whitened connective 
tissue which formed the sheaths of the muscle and the fiber 
bundles. 



MUSCLES. ii 

3. Lay a piece of round steak on a board. With a dull knife 
scrape the surface of the steak. Note the softness and redness 
of the pulp thus obtained, and the absence of connective tissue. 
In the remaining steak observe the empty sheaths of connective 
tissue. 

4. Take a number of pieces of red cord to represent muscle 
fibers. Wrap each in white tissue paper. The wrapper corre- 
sponds to the individual muscle-fiber sheath. Lay a number of the 
wrapped threads side by side and wrap all in a common sheath. 
Let the tissue paper project beyond the threads and compress the 
projecting part into a compact cylinder to represent the tendon. 

MICROSCOPIC STRUCTURE OF MUSCLE. 

Material. — A bit of lean meat of any kind. A mounted slide of striated 
muscle. 

1. Lay a tiny shred of lean meat on a slide in a drop of normal 
salt solution. With the handle of the scalpel press on one end of 
it to hold it in place. With a dissecting needle fray out the other 
end by drawing the needle through it lengthwise and gently sepa- 
rating the fibers at the end into a fan-shaped arrangement. Cover 
with a cover slip and examine, first with a low power (half-inch 
or two-thirds-inch objective) and then with the high power (one- 
fifth or one-sixth inch objective). On account of the cross 
markings this kind of muscle fiber is called striated or striped 
muscle fiber, and all muscles made up of such fibers are called 
striated muscles or striped muscles. All of the skeletal mus- 
cles have striated fibers. 

2. Can you distinguish the sheath of the individual muscle 
fiber? The muscle-fiber sheath is more readily seen where the 
muscle fiber is bent, torn, or twisted. 

3. Examine a prepared slide showing striated muscle fibers. 
Look for the features noted in the preceding paragraph. 

4. Make a sketch showing as many as possible of these 
points. 



12 PHYSIOLOGY. 

RELATIONS OF THE MUSCLES AND THE BONES. 
Material. — Human skeleton, or bones of the arm. 

i. Feel of the biceps muscle in your own arm. Locate the 
biceps on the humerus. (See Fig. 2, Part I.) Note that the 
thickest part of the muscle is opposite the slenderest part of 
the bone. Note also that at the enlarged ends of the bone the 
muscle has narrowed to a slender tendon, which passes over the 
joint to be attached to the next bone. This arrangement gives 
slenderness, flexibility, and freedom of motion to the joint. 

2. Take the bones of the arm of an articulated skeleton. If an 
articulated skeleton is not at hand, the bones of the arm may be 
hinged at the elbow. Put a strong rubber band in place of the 
biceps. Fasten it to the head of the humerus or to the shoulder 
blade. At the lower end attach the rubber to the radius about 
two inches from the elbow joint, where the rough place shows the 
attachment of the tendon. Have the rubber stretched so that 
when not held it will flex the forearm. But bear in mind that the 
muscle draws up the forearm, not because it has been stretched, 
but because of its ability, as a living muscle, to shorten. 

THE STUDY OF LEVERS. 

Material. — A foot rule. String. A triangular block, about an inch 
thick. 

1. Lay a book on the table. Insert one end of the rule under 
it. Lay the block under the rule about three inches from the 
book. Pry down on the other end of the rule and raise the book. 
The book is the weight, the block is the fulcrum, and the hand is 
the power. The fulcrum is between the power and the weight. 
It is a lever of the first class. 

2. Lay a book on the table. Push two inches of the rule un- 
der the book. Now lift the outer end of the rule. The fulcrum 
is now at the end of the lever where it rests on the table. The 
weight is where the book rests on the lever. The power is at the 



MUSCLES. 13 

hand. The weight is between the power and the fulcrum. Such 
a lever is called a lever of the seco?id class. 

3. Tie a string a foot long around the rule three inches from 
one end. Lay the lever on the table with the other end project- 
ing two inches over the edge of the table. By another string hang 
a weight, say a bunch of keys, on the outer end of the lever. 
With the thumb hold down the end of the lever that is on the 
table, while you pull upward on the first string. By means of 
this string you apply the power. At the outer end is the weight. 
The thumb is the fulcrum. The power is between the weight and 
the fulcrum. Such a lever is called a lever of the third class. 



LEVERS IN THE BODY. 

1. Study the foot and see how it may serve as a lever of each 
of the three classes. 

2. How may the forearm be used as a lever of the first class ? 
How of the second ? Of the third ? 

3. Explain the lever action of the head in nodding. 

4. What kind of a lever is the lower jaw when you bite with the 
front teeth ? Explain. 

5. Explain the action of other levers in the body. 



STUDY OF ONE OF THE LONG BONES. 
Material. — A femur, or a humerus. 

1. Observe its shape — cylindrical, somewhat curved, enlarged 
at the ends. 

2. The ends have smooth places, where they fitted other bones. 

3. Along the sides, especially near the ends, are ridges and 
projections, where the muscles were attached. 

4. There are small holes in the bone, where blood tubes passed 
in and out. 

5. Saw a femur in two, lengthwise, and make a drawing show- 



i 4 PHYSIOLOGY. 

ing : {a) The central marrow cavity, (b) The spongy extremities, 
noting especially the directions of the bony plates and fibers. 

6. Observe the width of the lower end of the femur, where it 
rests on the tibia. Suppose these two bones were as narrow at 
their ends, where they meet to form the knee joint, as they are at 
their centers, what kind of a joint would they make ? Illustrate 
by piling up a number of spools on end ; the column is more 
lightened than it is weakened by the hollowing out of the sides of 
each spool, and the central hollow of the spool does not greatly 
weaken it. A given weight of material has more strength when in 
the form of a hollow cylinder. Note carefully that this is not saying 
that a hollow pillar is stronger than a solid one ; but for the same 
weight of bone more strength is given by having it hollow. The 
bones combine well two very desirable qualities, lightness and 
strength. 

7. If in our column of spools we place a wide rubber band 
around the junction of two spools, we have something very similar 
to the capsular ligament. 

LOCOMOTION BY REACTION. 

Material. — A board ten feet long, one foot wide, and one inch thick, 
Two broomsticks. 

1. Lay the two broomsticks crosswise under the board and near 
its ends. Run along the board. What does this show ? 

2. Why is it so tiring to walk, especially if one tries to walk 
rapidly, on glary ice or on sleety sidewalks ? 

3. Study the action ot an animal in a treadmill. Does it 
progress ? Why not ? 

4. How does a bird make progress through the air? How 
does a fish make headway through the water ? 



CHAPTER III. 

THE SPINAL CORD AND SPINAL NERVES. 

DISSECTION OF THE SPINAL CORD AND SPINAL NERVES OF 
THE RABBIT. 

Material. — Rabbits ; remove the skin just before dissecting. Bone for- 
ceps. A support made as follows : Baseboard two feet long, eight inches 
wide, one inch thick ; a piece of scantling, two by four, sixteen inches long ; 
nail the scantling to the base with one edge along the middle line, leaving 
equal spaces at the two ends. Mounted skeleton of cat or rabbit. Human 
skull. Hammer. Four six-penny nails. A large sheet of manila, or straw, 
paper. 

i. If possible, have at hand a well-mounted skeleton of a cat or 
rabbit. Note carefully (a) the cavity of the cranium, (p) the 
cavity of the spinal column, and (V) the sides of each neural 
ring where the bone is to be cut by the bone forceps, as shown in 
Fig. 2. 

2. Open the chest cavity by cutting in on each side along the 
line where the bony parts of the ribs join the cartilages of the ribs. 
Remove the breastbone. Open the abdominal cavity along the 
middle line. Remove the heart and lungs and all the organs of 
the abdominal cavity. Lay a sheet of paper over the support to 
keep it from being stained in the next operation. 

3. Place the specimen on the edge of the scantling, which it 
should ride like a saddle. If necessary, bevel off the top of the 
scantling near the ends to fit the head and pelvis. Stretch out 
the feet and nail them to the baseboard. 

4. Cut away the muscles from the back of the neck and along 
the sides of the backbone. This can be done rapidly by making 
long, deep cuts with the cartilage knife along the sides of the 
backbone in the planes indicated in the accompanying figure. 



i6 



PHYSIOLOGY. 



5. Between the skull and the first vertebra is a space covered 
by a thin membrane, through which the spinal cord may be 
seen. Carefully cut through this membrane, and insert the point 
of one blade of the bone forceps at one side of the spinal cord. 
Cut through this side of the arch of the vertebra ; repeat the cut 
on the other side and so on, through the whole length of the 
spinal column. Do not separate the dorsal parts of the vertebras, 




Fig. 2. Diagram for -Dissecting Spinal Cord. 

Cut along 3 2 with cartilage knife. 



1. Cut along 1 2 with cartilage knife 

3. Cut along 4 with bone forceps. 



but keep the whole in one strip, held together by the connective 
tissue. The bony cavity in which the spinal cord lies is the 
neural cavity. 

6. Now look for the spinal nerves, which leave the spinal cord 
in pairs, right and left, between the successive vertebras. It will 
probably be necessary to cut away considerably more bone to 
expose the nerves. This dissection calls for hard work, and for 
great care and patience. 

7. Note carefully the variations in the diameter of the spinal 
cord in its course. The anterior swelling is called the cervical 
enlargement, and the posterior is the lumbar enlargement. 



THE SPINAL CORD AND SPINAL NERVES. 17 

8. When the spinal nerves have all been laid bare, count them 
and compare them as to their (a) size, (b) intervals between succes- 
sive pairs, and (c) angles at which they leave the spinal cord. 

9. Carefully cut away the bone around some of the largest 
nerves in the region of the shoulder, and find the two roots by 
which each nerve is connected with the cord, one nearer the back, 
the dorsal root, the other nearer the ventral surface of the body, 
the ventral root. Trace these two roots and note that they unite 
to form one spinal nerve. 

10. On the dorsal root, just before it joins the ventral, is a 
small swelling, the ganglion of the dorsal root. 

11. In the region of the shoulder carefully trace several of the 
nerves as they unite to form the brachial plexus, from which nerves 
supply the fore limb. 

12. In the region of the hips trace several of the spinal nerves 
to their union in the large sciatic plexus. 

13. Beyond the sciatic plexus several of the nerves unite to 
form the large sciatic nerve, which runs down the thigh. 

14. Turn now to the head and cut through the bone between 
the eyes. Cautiously work backward and unroof the whole of the 
brain. Great care must be used, for here we have one of the 
softest of the tissues of the body, lying very closely beneath one of 
the hardest. It is possible to do this with a strong knife, but the 
bone forceps save a great deal of hard work. The bone must be 
chipped and broken away, bit by bit. By slightly inserting one 
blade of the forceps under the edge of the bone, and then prying 
upward and outward, the bone may be broken away with less 
danger of injuring the brain. 

15. Compare the color of the brain with that of the spinal cord. 
The tough membrane covering the brain is the dura mater. 

16. The fore part of the brain is the cerebrum. Note the 
groove separating it into the right and left hemispheres. Observe 
the irregular ridges on its surface. These are the convolutions. 

17. The prolongations of the brain between the eyes are the 
olfactory lobes. 



18 PHYSIOLOGY. 

1 8. Back of the cerebrum is the cerebellum. Look at a human 
skull to see if there is a bony partition corresponding to that 
which separates the cerebrum from the cerebellum of the rabbit. 

19. The part of the spinal cord which is within the skull is 
called the spinal bulb. Note that it widens as it approaches the 
brain. It is considered as a part of the brain. 

20. Make a drawing of the brain and spinal cord, showing as 
many as possible of the points above noted. If desired, the 
brain and spinal cord, with a short portion of each nerve, may be 
removed and laid on a cushion of cotton in weak alcohol. 

STRUCTURE OF NERVES AND NERVE FIBERS. 

Material. — A piece of fresh nerve (frog or rabbit). Chloroform. Nor- 
mal salt solution. 

1 . Cut off a quarter of an inch of fresh nerve. Lay it on a 
slide. Hold one end by pressing with the handle of the scalpel, 
and tease out the other end by drawing a dissecting needle 
through it lengthwise. Spread out the separated fibers and put 
on a drop of normal salt solution. Cover with a cover slip and 
examine, first with a low, then with a high, power. 

2. Observe that the nerve is made up of fibers. Also that con- 
nective tissue surrounds the nerve and is between the fibers. 

3. In a single fiber observe (a) the thin transparent covering, 
the nerve-fiber sheath ; (b) inside this the medullary sheath, at first 
clear, later becoming white ; {c) in the center, the axis cylinder. 
To bring this out, add a drop of chloroform. 

STRUCTURE OF THE SPINAL CORD. 

Material. — Piece of fresh spinal cord (calf or rabbit). Prepared cross 
sections of spinal cord, some stained, others injected. Hand lens. 

1. With the naked eye examine the end of a fresh cut of 
spinal cord. The darker central part is the gray matter. Outside 
this is the white matter. 



THE SPINAL CORD AND SPINAL NERVES. 19 

2. With the naked eye examine the mounted cross section of 
spinal cord, holding it up to the light, or over white paper. The 
paler outer part is the white matter. Observe that the gray mat- 
ter has the form of a spreading letter H. 

3. Observe that between two of the arms of the H a crevice 
extends toward the center. This is the ventral fissure. 

4. The arm of gray matter on each, side of the ventral fissure 
is known as a ventral horn. The arms extending toward the sur- 
face opposite the fissure are the dorsal horns. 

5. Examine the section with a hand lens, say a tripod magnifier. 
Directly opposite the ventral fissure is a partition, extending well 
toward the center of the cord. This is the dorsal septum. 

6. Under a microscope with a two-inch objective note also 
many partitions extending inward to various distances. These are 
the septums of connective tissue, extending inward from the 
covering of the cord. 

7. Under a tvvo-thirds-inch objective note the strands extending 
outward from the tips of the horns. These reach the surface 
where the roots of the nerves arise. 

8. With a two-thirds-inch objective note the large angular 
nerve cells in the ventral horns. From their angles nerve fibers 
may be seen to originate. The staining matter gives these cells a 
deeper color than that of surrounding parts. 

9. With the same power examine the hole in the center of the 
cross bar of gray matter. This is the central canal of the cord. 

10. W T ith a one-sixth-inch objective examine the white matter. 
It is mostly made up of fibers, whose cross sections should now be 
seen. The darker central spot in each fiber is the cross section 
of the axis cylinder. Can you distinguish the medullary sheath and 
the nerve-fiber sheath? 

n. Examine the gray matter with a one-sixth-inch objective. 
Of which is it more largely composed, cells or fibers ? 

12. Examine a section of an injected spinal cord. Note the 
branching capillaries. In which are they more numerous, the 
gray or the white matter? 



20 PHYSIOLOGY. 



REFLEX ACTION OF THE FROG'S SPINAL CORD. 

Material. — Live frogs of good size. Retort stand. S-hook made of 
No. 1 6 brass wire, sharp at both ends. Knitting needle, or wire of equal 
diameter. 

Chloroform the frog as directed on p. 9. As soon as it is in- 
sensible, find, by bending the head, the joint between the head 
and the backbone. Lay the frog on a board and quickly thrust 
the blade of a scalpel through the body at this joint, and com- 
pletely sever the spinal column and spinal cord. This is essentially 
the same as cutting off the head. Through the opening back of 
the head, run a knitting needle, or wire, into the brain cavity 
and stir it about in order to destroy the brain. In a few minutes 
run the S-hook through both upper and lower jaws, just back of 
the snout, and suspend the frog from the ring of a retort stand. 

1. Pinch the toes with a pair of forceps; what follows? Re- 
peat the experiment several times. A slight pinch is usually suffi- 
cient. Pinch the skin near the anus. 

2. Slit the skin along the back of the thigh. Tear apart the 
muscles and find the white sciatic nerve. With a sharp pair of 
scissors (while closely watching the foot) sever the sciatic nerve 
at the middle of the thigh. What takes place? 

3. Hang the frog as before and pinch the toes of each foot. 
What difference is now observed? 

4. With the scissors alternately snip off a very short bit of each 
of the two ends of the severed sciatic nerve. What takes place 
as these two ends are cut? 

5. Run a wire down the spinal column, twisting it about to 
destroy the spinal cord. What occurs while one is doing this? 

6. Pinch the toes as before. What results? 

7. Again snip off a bit of that part of the sciatic nerve that is 
connected below. What action follows ? 

8. Repeat the experiments with the other thigh. 



CHAPTER IV. 

STRUCTURE AND ACTION OF THE HEART. 

THE HEART BEAT AND THE PULSE. 

i. Feel the heart beat at the left of the breast bone. 

2. Feel the pulse at the wrist and in various parts of the body. 
Lay the forefinger lightly along the cheek just in front of the ear. 
Count the pulsations for a minute. 

3. Let one or two pupils who are quick with figures step to the 
blackboard, and put down the number of pulsations of each pupil 
as reported when his name is called. Find the average for the 
class. 

4. Let all in the class count the pulse while sitting. Probably 
it will be well to discard the first trial, as there will likely be sev- 
eral failures, from one cause or another. Then, too, there is 
usually a slight excitement at the beginning of such an experiment 
for the first time. 

5. While sitting, find the pulse ; rise quickly, and immediately 
begin to count. Compare with the pulse rate taken while sitting. 

6. Again, after sitting quietly for some time, find the pulse. 
Rise quickly, begin counting immediately, and note the number 
at the end of a half minute, but count on continuously to the end 
of the minute. Compare the number of pulsations in the first 
half minute with that of the second half. 

7. Stand and take active exercise for a few minutes. Imme- 
diately count the pulse. 

8. At home count the pulse while lying down, after remaining 
in that position for half an hour. 

9. Compare the pulse before and after meals. 

10. With the thumb and finger lightly clasp the windpipe, well 
back. The pulse in the carotid artery will be felt. 



22 PHYSIOLOGY. 

DISSECTION OF THE HEART AND LUNGS. 

Material. — The heart and lungs (pluck) of sheep, calf, or pig. One 
pluck for each two students. Wooden faucets, size No. 2 or No. 3 (from 
seven to nine inches long), one for each two students. An abundant supply 
of heavy manila, or straw, paper. Two sheets about eighteen by twenty- 
four inches under each pluck. Renew the papers if they become soaked. 
Corks, three fourths of an inch in diameter, one for each pluck. 

i. Hold the mass up by the windpipe, with the heart away 
from you. The end now uppermost is the anterior end ; below 
is the posterior end ; the lung to your right is the right lung ; to 
your left is the left lung; the surface nearest you is the dorsal 
surface ; opposite is the ventral surface. The anterior end of the 
lung is its apex. The posterior end is the base. The smooth, 
moist, glistening membrane covering the lung is the pleura. 

2. Observe the windpipe, or trachea, with its stiff rings of 
gristle or cartilage. The thick part of the anterior end is the 
larynx. 

3. Running along the dorsal surface of the windpipe is a soft 
red tube, the gullet, or esophagus. At about the middle of the 
windpipe, separate the gullet and windpipe for three or four 
inches. Note that next to the gullet the windpipe is soft and 
yielding where the gaps of the C-shaped cartilages are filled in 
with muscular and elastic tissue. Make a slit, two inches long, in 
this soft membrane. 

4. Inflate the lungs as follows : Take a wooden faucet and 
slip into the slit in the windpipe the end of the faucet that goes 
into the barrel. Now take hold of the windpipe above the slit 
and hold in such a way as to pull the windpipe up and at the 
same time press the faucet down. Inflate through the spout, then 
shut off the air. If the lungs have not been punctured, they 
should now remain distended. If necessary, tie the faucet in. 

5. Note: {a) the conical shape of the whole; compare this 
with the chest cavity as shown in a skeleton ; {b) how the lungs 
nearly surround the heart; (c) the concave posterior surface of 
the lungs where they fitted the convex anterior surface of the 



STRUCTURE AND ACTION OF THE HEART. 23 

diaphragm ; (d) the groove between the dorsal surfaces of the 
lungs, in which the spinal column fitted ; {e) the smooth, un- 
divided dorsal surfaces of the lungs, and their division ventrally 
into lobes ; (/) the relative lengths of the dorsal and ventral sur- 
faces of the lungs. 

6. Open the valve of the faucet. What makes the air go out? 
Again innate. Does it require effort to do so? Why? Cut off 
the end of one lobe and again inflate. Does the air escape? 
Throw a piece of lung on water. Pinch a piece of lung, holding 
it near the ear. 

7. Observe a large whitish or yellowish tube running in the 
groove between the dorsal surfaces of the two lungs. It is usually 
covered by fat, and may have been cut off short, so that its open 
end is readily seen near the windpipe. This is the main artery, 
the aorta. Take hold of its free end and separate it from its 
attachment to the other tissues, cutting close to it with the scissors 
up to the place where it arches over the root of the left lung. 
Now turn the free end forward over the left lung. 

8. Find where the gullet is cut off posteriorly. Slit it open for 
an inch or two. The thick, red, outer coat is the muscular coat. 
The whitish lining is the mucous coat. Beginning posteriorly, 
separate the gullet from the windpipe, cut off the windpipe at 
about its middle, and entirely remove the gullet and larynx. 

9. Examine the windpipe. Insert a finger and stretch it. Note 
its C-shaped cartilages. Its lining is a mucous membrane. 

10. Lay the heart and lungs on their ventral surface, with the 
posterior end toward you. Using the handle of the scalpel as a 
chisel, clear away any tissue covering the windpipe and trace it 
toward the lungs. Each of the main branches of the windpipe is 
a bronchus. How many bronchi are there? Here are often 
found small oval, brownish bodies, the lymphatic glands, em- 
bedded in connective tissue. Scrape these loose with the scalpel 
handle. 

11. Lay the lungs on their dorsal surface, with the anterior 
end toward you. Note how easily the heart may be moved about 



24 PHYSIOLOGY. 

in its case, the pericardium. With scissors slit the pericardium 
along its ventral surface and observe the smoothness of its lining 
and of the surface of the heart. Note also the pericardial liquid. 

12. Carefully compare the right and left sides of the heart. 
Running obliquely across the surface of the heart is a groove, in 
which are blood tubes, often covered by fat. The part to the 
right of this groove is the right ventricle. On the left of the groove 
is the left ventricle. 

13. At the base (anterior end) of the heart on each side are the 
right and left auricles. 

14. Tip up and toward you the apex of the heart. Compare 
the width and thickness of the heart. Compare the dorsal and 
ventral surfaces as to the length, convexity, etc. Press the two 
ventricles and compare them in firmness. 

15. Turn the heart to the left and examine the right auricle. 
Find a large, flabby red tube entering its anterior surface ; this is 
the precaval vein. Prick a small hole in the precaval vein close 
to the pericardium and insert the tip of the blowpipe ; hold firmly 
around the opening and inflate. This should show the outline of 
the right auricle. Meanwhile watch closely the dorsal part of the 
auricle ; the postcaval vein should now be discovered, entering the 
auricle from the posterior region. Look for it on the dorsal side 
of the pericardium, where it runs anteriorly from the diaphragm. 

16. Turn the heart to the right and observe a large, light-col- 
ored tube arising from the base of the right ventricle, between the 
two auricles. This is the pulmonary artery. 

17. Again turn the heart to the left and raise the right auricle. 
Arising from the center of the base of the heart is the large, whitish 
aorta. Carefully separate the aorta from the pulmonary artery 
and from all other tissues, and trace it as it arches over the left 
bronchus and runs down between the two lungs close to the gullet. 
Clear away any fat or other tissue adhering to it. With the 
scissors carefully trim away the pericardium. 

18. From the arch of the aorta arise the branches running to 
the head and fore limbs. How many are there ? 



STRUCTURE AND ACTION OF THE HEART. 25 

19. In the same way trace the pulmonary artery till it forks to 
the right and left lungs. 

20. When the fork of the pulmonary artery has been reached, 
lay the heart and lungs on their ventral surface, with the posterior 
end toward you. Turn the windpipe back toward you and with 
the handle of the scalpel trace the branches of the pulmonary 
artery into the lungs. Cut them off close to the lungs. 

21. Now trace the pulmonary veins. These are to be found on 
the ventral side of the bronchi. Their general outlines may be 
shown by inflating as follows : Cut off the first branch of the 
aorta as close as possible to the arch. Insert one blade of the 
scissors into this opening, pointing away from the heart, and make 
a slit two inches long. Insert a cork toward the heart. It 
should fit snugly, so that air may not escape. For a pig's heart, 
a cork about three fourths of an inch in diameter at its larger 
end is about right. 

22. Make a very small hole in the tip of the left auricle, insert 
the tip of the blowpipe, holding firmly around it, and inflate. 
This should distend the left auricle and the pulmonary veins. 
With the handle of the scalpel scrape away any fat or other tissue 
that covers the pulmonary veins and trace Jhem from the lungs to 
the left auricle. How many are there ? Cut off the left bronchus 
close to the lung and turn the windpipe to the right. Clear the 
pulmonary veins from any tissue that lies under them. 

, 23. Turn now to the ventral surface of the heart. Lift the ventral 
margin of the flap of the left auricle and with the scissors cut into 
the cavity of the left auricle through the bottom of the groove 
between the left auricle and the left ventricle. Make a slit an 
inch long, following the groove. Pass a probe into the opening 
and across the cavity of the auricle. On the dorsal wall of the 
auricle are the entrances of the pulmonary veins. Pass the probe 
into the pulmonary veins and trace them to the right and left 
lungs. Cut them off near the lungs. 

24. With the scissors slit down one bronchus through the lung, 
noting its branches. Follow the outside of another bronchus, 



26 PHYSIOLOGY. 

tearing away the lung tissue with the handle of the scalpel. 
Save the heart for further study. 

DISSECTION OF THE HEART. 

Material. — Pig hearts or sheep hearts, one for each student, or one for 
each two. Papers on which to dissect. 

i. Briefly review the parts of the heart: precaval vein ; post- 
caval vein ; right auricle ; right ventricle ; pulmonary artery ; 
pulmonary veins ; left auricle ; left ventricle ; aorta. Hold the 
heart suspended by the aorta and dance it up and down to show 
the elasticity of the aorta. Cut off the aorta where the slit was 
made at the arch, and feel its inner surface. 

2. Run a probe into the precaval vein, through the right 
auricle and out of the postcaval vein. With scissors cut along 
the upper side of the probe and explore the cavity of the right 
auricle. Feel the inside of the auricle and the veins. Observe 
that the cavity of the auricle extends farther into the heart than 
the notch between the auricle and the ventricle. ' Note the 
muscular columns within the appendage of the auricle. At the 
extreme left of the right auricle is the mouth of the cardiac vein, 
which, running around between the left auricle and left ventricle, 
brings blood from the ventral wall of the heart. Near the mouth 
of this vein also empty the veins seen in the dorsal wall of the 
heart. Pick out any clots that may be found. 

3. Cut away the whole of the appendage of the right auricle. 
Remember that the pulmonary veins from the right lung run very 
close to the right auricle and be careful not to cut into them. 
Hold the heart in the left hand with the ventral surface in the 
palm, and the tips of the fingers against the right ventricle. Hold 
the heart under a faucet, or pour from a pitcher, and let the water 
run, first gently, then strongly, through the right auricle into the 
right ventricle. Watch the aur-vent valves (short for auriculo- 
ventricular) as they float up and separate the auricle from the 
ventricle. If clots are found back of the valves, they must be 



STRUCTURE AND ACTION OF THE HEART. 27 

carefully washed out or picked out. Empty the heart again and 
once more hold it under the stream of water. As soon as the 
valves rise, press with the fingers on the outside of the ventricle. 
What effect has this pressure ? Let the nozzle of the faucet down 
between the valves and again turn on the water. Where does the 
water escape? 

4. Empty the heart again and examine the valves. They will 
be found lying close against the walls of the ventricle. Note the 
white tendinous cords attached to the valves. 

5. Push the forefinger of the left hand past these valves to the 
very bottom of the ventricle. From the outside, with scissors, cut 
through the wall of the ventricle at this point. Continue the cut 
upward along the border of the ventricle, stopping half an inch 
from the base of the ventricle. In the same way cut up along the 
other border of the ventricle, stopping short of the auricle. Raise 
the outer wall of the ventricle and study the valves more thor- 
oughly. With the forceps raise them from the walls of the ven- 
tricle. How many flaps are there? How are they arranged ? This, 
the right aur-vent valve, is often called the tricuspid valve. 
The conical elevations of muscle to which the tendinous 
cords are attached are the papillary muscles. How are the valves 
held in place? How are they acted on and how do they act? 

6. Find the connection between the right ventricle and the 
pulmonary artery. Pass a probe up into the pulmonary artery. 
Cut away enough of the wall of the ventricle to show the begin- 
ning of the artery. Gut off the pulmonary artery just before it 
forks to the two lungs. Slip the end of the artery over the end 
of the faucet and turn on a very little water. Watch closely the 
base of the artery. If necessary, turn on a little more water to 
show the filling of the pocket-like vent-art valves (short for 
ventriculo-arterial \ often called semilunar). Note their number, 
shape, and arrangement. What is the effect of the stream of 
water on them and what is their effect on the stream of water? 

7. Examine the left auricle and find where the pulmonary veins 
enter it. Cut away the lobe of the left auricle. Examine its 



28 PHYSIOLOGY. 

inner surface and find the openings of the pulmonary veins. 
Hold the heart under the faucet and prove the action of the 
left aur-vent valve, between the left auricle and left ventricle. In- 
sert the nozzle of the faucet between the valves and again turn on 
the water. Where does it escape ? Cut off the aorta half an inch 
from its base and repeat the last experiment with the water, 
meanwhile closely watching the vent-art valves of the aorta. 

8. Above the pockets of the aortic vent-art valves look for the 
openings of the cardiac arteries, which supply the walls of the 
heart. Probe them. How many are. there? Can you trace 
them on the outside of the heart? 

9. Pass the handle of the scalpel between the aortic vent-art 
valves, into the left ventricle ; it passes back of one flap of the 
left aur-vent valve. 

10. Slit open the left ventricle. Note the strong muscular 
columns and the strong papillary muscles. The left aur-vent 
valve is usually called the mitral valve. Note that, though end- 
ing in two flaps below, it is continuous at the top. Compare the 
walls of the left ventricle with those of the right. Why this differ- 
ence? Note the partition between the ventricles. Is there any 
direct communication between the right and left halves of the 
heart ? 

11. Slit open the aorta between two of the pockets of the 
vent- art valve and study the valve more closely. In the middle 
of the free border of each flap note the little thickened point. 
When the valves close, these three points fill a small three-cor- 
nered space that would otherwise be left between the valves. 
Again examine the cardiac arteries. 

12. In another heart carefully cut around the base of the 
pulmonary artery, avoiding any injury to the valves. Tie the 
outer end of the artery over the end of a large tube, half-inch or 
more in diameter. A glass tube is so slippery that it is difficult 
to keep it from slipping. Before inserting the glass tube into the 
artery, slip a short piece of rubber tube on the end of the glass 
tube. Now blow suddenly and forcibly into the glass tube. This 



STRUCTURE AND ACTION OF THE HEART. 29 

should show the action of the vent-art valves. The valves work 
better when moist and flexible. It is therefore better to keep the 
artery standing in a tumbler of water till it is to be used. For 
convenience let one student demonstrate this, passing around so 
all can see it clearly. 

13. Longitudinal and cross sections of a frozen heart are 
instructive, 

THE ACTION OF THE FROG'S HEART. 

Material. — Large frog. Chloroform or ether. Quart jar. 

1. Kill a frog as directed on p. 9 and destroy its brain and 
spinal cord. Carefully open the body cavity and lay bare the 
heart without injuring it. 

2. Study the heart-beat. Note that it consists of three parts : 
(a) the contraction of the auricle ; (J?) the contraction of the 
ventricle ; (V) the pause, after which the whole cycle is repeated. 

3. Breathe en the heart. Does this affect it? Touch it with 
a test tube containing warm water ; with hot water. 

4. Touch the heart with a test tube filled with ice water. 
What effect? Lay a piece of ice on the heart. 

5. Try salt solutions, of varying degrees of strength, on the 
heart. What result? 

6. Is the heart affected by being pricked by a needle ? 

DEMONSTRATION OF THE ACTION OF THE HEART. 

Material. — A good-sized sheep or pig pluck, or a calf pluck. Apparatus 
shown in Fig. 17, Part I. String. Quart cups. 

Get the heart and lungs entire. Dissect out the aorta as di- 
rected on p. 24. Clear the pulmonary artery and cut off both 
branches close to the lungs. Carefully trim away the pericardium 
and clean the precaval and postcaval veins. Turn the heart back 
and find one of the larger pulmonary veins ; cut a hole in it near 
the lung and slip a glass tube into it toward the heart ; to keep the 
glass tube from slipping out slip a piece of rubber tube, an inch or 



30 PHYSIOLOGY. 

two long, over the end of the tube, but not projecting beyond the 
end of the glass tube. If this fits snugly, it will not slip on the glass 
tube and the blood tubes will hold firmly when tied over the rub- 
ber. It is much better to tie the tube into the pulmonary vein 
before the vein is cut off; otherwise there will be difficulty on ac- 
count of the shortness of the pulmonary vein ; tie the tube firmly 
in, and tie the other pulmonary veins without stopping to trace 
them. Tie any and all connections with the heart now remaining 
and cut beyond the place tied. Get a retort stand and two large 
glass funnels, or have made a more convenient piece of apparatus 
(as shown in Fig. 17, Part I) consisting of a sheet-iron pan 
eighteen inches square and two inches deep, with a fixed bail 
handle twenty inches high, made of iron rod of the size of a retort- 
stand rod. Attach retort rings to the upright rod, as shown in the 
figure. This whole apparatus, with the heart attached according 
to the directions given, can easily be carried, and any overflow of 
liquids will be caught by the pan. Place the funnels in the rings. 
Lay the heart, now wholly severed from the lungs, on its ventral 
surface. Connect one funnel, by rubber and glass tubing, with 
the left auricle by the tube already in the pulmonary vein ; con- 
nect the other funnel with the right auricle through the precaval 
vein ; tie the postcaval vein. Lay the heart in a basin and pour 
water into the funnels; hold the heart with the two hands and 
compress it, repeatedly adding water. In this way the clotted 
blood usually present in the right ventricle may be washed out. 
If this remain, it may interfere with later experiment. Con- - 
nect the aorta with the funnel which leads to the right auricle, by 
means of a glass tube which arches above and is held in place by 
a clamp, thus emptying into this funnel any liquid which escapes 
from the tube. 

In like manner have a bent glass tube, from the pulmonary 
artery, clamped above the funnel leading to the left auricle. 

If possible, let the heart soak in water over night before showing 
it to the class. This will loosen the clots and make the valves 
more flexible. 



STRUCTURE AND ACTION OF THE HEART. 31 

Pour water into one of the funnels and compress the heart to 
imitate its natural contraction ; observe where the liquid next ap- 
pears ; add more water and follow it around to its starting point. 
A little ink may be poured into one of the funnels and traced 
around, as the heart is worked, to its starting point. 

That there is no direct connection between the two halves of 
the heart may be shown by changing the two hooked tubes so that 
the liquid from each artery empties into the funnel connected 
with the auricle of the same side of the heart. Different colored 
liquids may be used in the two funnels. 

In order to illustrate more fully how the heart is composed of 
two pumps fastened together and each pumping its own stream, 
but worked by the same power, try the following : — 

Take the two funnels supported as in the preceding experiment; 
connect each funnel with the supply tube of a common bulb 
syringe ; connect the delivery tube with the bent tubes used with 
the heart. 

1. Let each bent tube empty into the funnel from which it gets 
its supply. There are now two distinct circuits. 

2. Now cross the delivery tubes so that each discharges into the 
funnel from which the other gets its supply. Now, on working 
the bulbs, we have a circuit like a figure 8, really one circuit, but 
the two streams cross each other. 

3. Again, place the two bulbs side by side and work the two 
with one hand. 

4. Wrap a cloth around the two bulbs so that what is contained 
in the cloth cannot be seen. We have now a structure like the 
heart, but we know its structure. We know that it consists of two 
pumps wrapped together and working together; that is, by the 
same stroke, but with two wholly independent currents. 



CHAPTER V. 

STRUCTURE AND ACTION OF THE BLOOD TUBES. 

DISTRIBUTION OF THE ARTERIES AND VEINS IN A CAT OR 

RABBIT. 

Material. — A rabbit or cat with the arteries injected. Directions for 
injecting are given on p. 40. Large sheets of paper. 

1. The main artery, the aorta, is a thick-walled tube springing 
forward from the center of the base of the heart. It soon arches 
over to the left, turns backward, and runs along the middle of the 
dorsal wall of the chest cavity, close to the backbone. 

2. At the bend, or arch, the aorta gives off two branches (three 
in man). The first of these soon subdivides into three branches. 
The first branch, the right subclavian artery, runs to the right fore 
limb. The second and third subdivisions extend along the sides 
of the windpipe, and are called the right and left carotid arteries. 
The second branch of the aorta runs to the left fore limb and is 
the left subclavian artery. 

3. During its course through the thorax the aorta is called the 
thoracic aorta. Trace it to the point where it passes through 
the diaphragm. It then becomes the abdominal aorta. Turn the 
stomach and intestines over to the right and observe the abdominal 
aorta running along the dorsal wall of the abdomen. Just pos- 
terior to the diaphragm a branch is given off which divides, giving 
branches to the stomach, liver, pancreas, and spleen. 

4. Farther back a large branch is given off to the small 
intestine. This is the anterior mesenteric artery. Trace it as it 
branches through the mesentery. Posterior to the mesenteric artery 
are the branches to the kidneys, the renal arteries. Finally the 

32 



STRUCTURE AND ACTION OF BLOOD TUBES. 33 

aorta divides into two large branches, the common iliac arteries, 
supplying the hind limbs. 

5. Turn the stomach and intestines to the left and observe 
the two veins coming forward from the hind limbs. These are the 
common iliac veins. By their union they form the postcaval vein. 

6. Observe the veins from the kidneys, the renal veins. 

7. Trace the postcaval vein forward. It passes by the liver, 
through the diaphragm, and on to the right auricle. 

8. Observe the vein that gathers the blood from the intestine, 
the mesenteric vein. This vein is joined by a vein from the stom- 
ach, the gastric vein • by a vein from the spleen, the splenic vein ; 
by one from the pancreas, the pancreatic vein. These four veins 
form the portal vein, which empties into the liver. Unlike other 
veins, the portal vein subdivides, distributing the blood through the 
liver. The blood thus distributed through the liver is collected 
again, and, by the hepatic veins, is poured into the postcaval vein, 
close to the diaphragm. The hepatic veins are almost wholly 
concealed by the liver. 

9. On removing the skin from the neck there should be found 
on each side the large jugular vein. Each of these is formed by 
the union of the external and internal jugular veins. 

10. Just before each jugular vein enters the chest cavity it is 
joined by a vein coming from the corresponding fore limb, the 
right and left subclavian veins. The union on each side forms 
the innominate vein. The two innominate veins unite to form the 
precaval vein, which enters the right auricle. In the rabbit there 
are two precaval veins. 

PLAIN MUSCLE FIBER. 

Material. — A prepared slide of the fibers of plain muscle. 

1. Examine with a high power. Note that each fiber is spindle 
shaped, and that it has no cross markings, or striations, such as 
were seen in the striated muscle fiber. Note the central nucleus. 



34 ' PHYSIOLOGY. 

TO REPRESENT THE STRUCTURE OF AN ARTERY. 

Material. — White rubber tube, half an inch in diameter. Red cord. 
White tissue paper. 

i. Wind the red cord closely around the rubber tube. The 
red cord represents the circularly arranged plain muscle fibers. 
To be more exact, there should be many short pieces of cord, 
instead of one long cord. Short pieces might be used by gluing 
them to the rubber tube. 

2. Wrap white tissue paper outside of the red cord. This 
represents the outer coat of the artery. 

CIRCULATION OF BLOOD IN THE WEB OF A FROG'S FOOT. 

Material. — Medium-sized frog with pale webs. Piece of shingle, cigar- 
box cover, or other thin board, six inches long and three inches wide. Make 
a round hole half an inch in diameter, one inch from the end of the board. 
Towel. Thread. 

i. Wrap the frog in a wet cloth and tie it, thus wrapped, to 
the board, with a foot over the hole. Tie threads around two of 
the longer toes and stretch the web over the hole. Be careful 
not to stretch it too tightly, or you may stop the circulation. Place 
the shingle firmly on the stage of a microscope. Support the 
outer end of the board at the level of the stage. A tumbler is of 
about the right hight for a support for most microscopes. 

2. Examine first with a low power. The large tubes that 
grow smaller by subdivision are the arteries. The large tubes that 
are formed by the union of smaller ones are the veins. The finer 
tubes forming a network in every direction are the capillaries. 
They receive the blood from the arteries and pass it on to the 
veins. 

3. Does the blood flow at the same rate in the arteries, capil- 
laries, and veins? Which has the most rapid rate? Which the 
slowest? 

4. Watch the flow in an artery. Is the flow steady? Or does 
it vary from time to time? How is this explained? In the same 
way watch the flow in a capillary and in a vein. 



STRUCTURE AND ACTION OF BLOOD TUBES. 35 

5. Put on a high-power objective, and study the corpuscles. 
Note (a) the large, faintly colored elliptical colored corpuscles. 
What is their color? What is their shape? Are they rigid, or 
flexible? Elastic or inelastic? Watch one as it turns a corner. 
(Jf) The smaller, rounded, paler bodies are the colorless corpuscles. 
What is their shape ? How do they compare in size with the col- 
ored corpuscles ? Note that they often move with a jerky motion, 
seeming to stick to the side of the tube, and then start on sud- 
denly. 

EXPERIMENTS ILLUSTRATING THE PULSE AND THE FLOW 
IN THE CAPILLARIES. 

Material. — 1. A common rubber bulb-syringe. 2. A glass tube, three 
feet long, seven sixteenths of an inch outside diameter. 3. Four inches of 
the same size glass tubing, for making connections. 4. Several nozzles, made of 
the same size glass tubing, all fine, but of varying degrees of fineness. 5. India 
rubber tubing, twelve feet long, three eighths inch inside diameter. This should 
be black, pure gum rubber, which is more highly elastic than the other kinds. 
6. Three feet of the same rubber tube as number 5. 7. Four inches of white 
rubber tubing, same size as above, for making connections. 

In all the experiments be careful to observe the following direc- 
tions : (a) Count aloud to mark the exact time of each compres- 
sion of the bulb, so the students can compare this with the time 
and duration of the jets of water, (b) Have an assistant hold the 
outlet tube so that (1) all members of the class can see the stream, 
and (2) that the stream may be suitably directed, as into a pail, 
or sink. (Y) Be careful to use very clean water, as any fine par- 
ticles of sediment are likely to clog the fine outlet of the nozzle. 
It is well to take the further precaution not to let the supply tube 
extend to the bottom of the water supply dish, as there may be 
some sediment in spite of previous care, (d) Round the ends of 
the glass tubes in the flame, or by filing. If sharp, they may 
scrape fine pieces off the inside of the rubber tube which may 
clog the nozzle. If this occurs, take off the nozzle and blow 
through it from the tip. Cut off the delivery tube of the syringe 



36 PHYSIOLOGY. 

about two inches from the bulb. Make all connections here as 
short as possible in order to get rid of elasticity in experiments i 
and 3. 

1. Put on, as a delivery tube, the long glass tube. Work the 
syringe (not forgetting to count aloud) and note that the jet is 
jerky, quickly following each compression of the bulb. 

2. Substitute the short black rubber tube (number 6) for the 
glass tube. On working the bulb the stream will still be found 
intermittent. 

3. Take off the rubber tube and replace the glass tube, adding 
a glass nozzle. Make the connection by means of the short piece 
of white rubber tubing. Now the pressure will be so great that it 
is likely to push off the nozzle, unless the assistant holds it very 
firmly. On working the bulb, greater effort must be made on 
account of the resistance caused by the narrower outlet. 

4. Once more substitute the short black rubber tube (number 
6), this time with a glass nozzle. Now, on working the bulb, 
resistance will be felt as before. Note also that the stream is 
nearly constant and continues for some time after ceasing to work 
the bulb. This is clearly because the rubber has been stretched 
by the pressure inside, and is now stretching back. That is, the 
elastic reaction of the rubber tube has converted the jerky action 
of the bulb into the steady flow now shown. 

In the first experiment we had a rigid tube, with practically 
no resistance. In the second, although the tube was elastic, there 
was almost no resistance, so the elasticity was not brought into 
play. In the third there was resistance, but the tube was inelastic. 
In the fourth the resistance of the narrow outlet brought into play 
the elasticity of the rubber tube, and the elastic reaction of the 
tube continues (so to speak) the action of the bulb between two 
successive strokes. 

5. Repeat the last experiment, except with the change of using 
the long rubber tube (number 5). Double this tube on a long 
table, so that the nozzle lies close to the bulb with the operators 
at the end of the table. Let the assistant hold the nozzle firmly. 



STRUCTURE AND ACTION OF BLOOD TUBES. 37 

As you work the bulb, count aloud and note how many strokes 
are made before the water begins to issue from the nozzle. Let 
the members of the class approach the end of the table hold- 
ing the bend of the loop. One row is to pass on each side toward 
the operators. Each student is to take hold of one side of the 
loop with one hand and of the other side of the loop with the 
other hand. Hold with a very light pressure of the thumb and 
forefinger. As the teacher compresses the bulb he counts aloud 
" one, two, three," " one, two, three," etc. At the end of each 
third count, each student takes a step forward. Thus he feels, in 
succession, from the bend of the loop to the other end, where one 
hand is near the bulb and the other hand near the nozzle. Ob- 
serve (1) the pulse; (2) whether the pulse occurs at the exact 
time of the compression, as indicated by the count ; (3) whether 
the pulse is felt at the same instant by the two hands ; (4) whether 
there is the same interval between the two impulses when near 
the bend and when one hand is near the nozzle and the other 
hand is near the bulb. Explain all these facts. 

6. Empty the rubber tube by continuing to work the bulb after 
lifting the supply tube out of the water. How long does the jet 
continue after ceasing to work the bulb? The pulse must not be 
confounded with the flow of the water itself. To show this, first 
empty the tube. Begin to fill up and note how long it takes to 
fill the tube. The pulse is a wave running very much faster than 
the liquid can run. 

7. Into a second dish pour enough red ink to color the water. 
While working the bulb, quickly transfer the supply tube to the 
red liquid. Continue working the bulb. Feel the pulse after 
each stroke. How long does it take for the pulse to run from 
the bulb to the nozzle ? How long does it take for the red liquid 
to run from the bulb to the nozzle ? 

On account of the elasticity of the arteries and the resistance 
due to friction in the capillaries, the pulse disappears on entering 
the capillaries and does not reappear in the veins. A pulse in the 
capillaries might rupture them, since they have such thin walls. 



38 PHYSIOLOGY. 

THE VALVES IN THE VEINS. 
Material. — A cat is much better for this work than a rabbit. 

i. Dissect back the skin from the throat of a cat, dog, or rabbit, 
till the jugular veins are well exposed. Let the head of the ani- 
mal hang over the edge of the table. Note that as the blood 
presses back toward the head it causes marked bulging at certain 
points. With the handle of the scalpel slightly stroke the vein 
toward the head, meanwhile watching these bulging points. The 
bulge indicates the presence of the pocket-like valves of the 
veins. 

2. Dissect out the jugular vein from the head to the shoulder. 
Insert the nozzle of a syringe, first into one end and then into the 
other, and show the effect of forcing currents in each direction. 

3. Slit the vein open along one side and pin it, inside out, to 
a piece of thin board. Examine the thin pocket-like, venous 
valves. With forceps lift the edges of the pockets. How are the 
mouths of the pockets placed in reference to the stream of blood 
in the vein ? 

4. Note the smoothness of the inside of the vein. Test the 
elasticity of the vein. 

5. Remove a piece of an artery and experiment with it as with 
the vein. 

MODEL ILLUSTRATING THE VALVES IN THE VEINS. 

Make a cloth tube, or take the Ijning of a boy's coat sleeve. 
Sew three patch pockets on the inside, in a circle, i.e. with their 
edges touching each other. Make the pockets a little "full." 
Pour sand, shot, or grain through the sleeve, first in one direction 
and then in the other. 

EXTERNAL INDICATIONS OF THE VALVES IN THE VEINS. 

1. With the forefinger stroke one of the veins on the hand or 
wrist toward the tips of the fingers. The vein swells out. The 



STRUCTURE AND ACTION OF BLOOD TUBES. 39 

blood meets resistance in the valves of the vein» The location of 
the valves is marked by the bulging of the vein at certain points. 

2. Stroke a vein toward the body. Is there any evidence of 
resistance as in previous experiment ? 

3„ Let the hand hang by the side. Note the large vein along 
the thumb side of the wrist. Place the tip of the second finger on 
this vein just above the base of the thumb. Now, while pressing 
firmly with the tip of the second finger, let the forefinger, with 
moderate pressure, stroke the vein up the wrist. It may be seen 
that the blood is pushed on freely, but comes back only part of 
the way. It stops where it reaches the valves, filling the vein full 
back to this point, but leaving it collapsed farther back, as shown 
by the groove. Remove the tip of the second finger and the 
vein immediately fills from the side nearer the tip of the 
finger. 

4. In a thin person the valves in the veins of the neck, or per- 
haps on the arm, may be located. 

5» These experiments show that the blood in the veins moves 
freely toward the body, but cannot flow outward toward the 
extremities. 

EXPERIMENTS ILLUSTRATING THE EFFECT OF GRAVITY ON 
CIRCULATION. 

Let all the pupils in the class stand. Hold one arm up straight 
so far as the clothing will readily permit. Let the other arm 
hang freely by the side. Observe : 

1. The difference in the color of the two hands. 

2. The difference in fullness, both in the feeling of fullness, and 
in the prominence of the veins, 

3. The difference in temperature. Place the backs of the two 
hands against the cheeks. 

4. The difference in position largely determines the amount of 
blood in the hand, and the amount of blood determines the color, 
the size, and the temperature. 



40 PHYSIOLOGY. 

DISSECTION OF THE SYMPATHETIC NERVOUS SYSTEM. 

Material. — Cat or rabbit. 

io Open the chest cavity of a cat or rabbit and pull the heart 
and lungs to one side. Along each side of the spinal column there 
should be found a white nerve cord, with a swelling on the side of 
each vertebra. This is the chain of the sympathetic nervous sys- 
tem. Each swelling is a ganglion. 

2. Find a nerve branch from each ganglion disappearing in the 
soft tissue between each two successive ribs. Pick away the sur- 
rounding tissue and trace this branch till it joins the corresponding 
spinal nerve. 

3. In this way follow down the spinal column. Are there as 
many ganglions as there are vertebras ? 

4. Trace the sympathetic nerve chain up along the neck. 
What do you find here as regards the number and size of the 
ganglions ? 

5. Trace the nerve chain through the diaphragm. On the 
dorsal surface of the stomach look for the network known as the 
solar plexus. 

INJECTION OF THE ARTERIES. 

The arteries and veins, unless distended with blood, are so 
nearly of the same color as the surrounding tissues that it is diffi- 
cult to distinguish them. Hence it is very desirable to fill them 
with some colored substance. 

STARCH INJECTION MASS. 

The following starch preparation, recommended in Anatomical 
Technology (Wilder and Gage), has been found very satisfactory. 

Dry starch (" Laundry " is good) . 100 c.c. 

Water, or a 2\ per cent aqueous solution of chloral hydrate. 100 c.c. 

Alcohol (95 per cent) 25 c.c. 

Color mixture (as given below) .... 25 c.c. 



STRUCTURE AND ACTION OF BLOOD TUBES. 41 

" After thoroughly mixing the mass, it should be filtered through 
one or two thicknesses of moistened paper cambric. To prevent 
the starch from settling, the cloth should be tilted from side to 
side, or the mass may be stirred during the filtration. If the mass 
is not freshly prepared for every injection, the stock mass should 
be filtered occasionally to remove hair or any other object that 
might clog the cannula. 

" Since almost any animal injected may afford some organ worth 
preserving, it seems better to employ permanent colors in tingeing 
the mass. Among those which are available, the following, prob- 
ably, are preferable : Vermilion, red lead, ultramarine, Berlin blue, 
chrome orange, yellow, or green." 

PREPARATION OF THE COLOR. 

Dry color . . . 100 c.c. 

Glycerine .......... 100 c.c. 

Alcohol (95 per cent) 100 c.c. 

" To avoid lumps, which would clog the cannula, or small blood 
tubes, the color should be thoroughly ground in a mortar. It 
should be stored in a well-stoppered bottle, and is prepared for 
use by simply shaking. If permanent preparations are not to be 
made, the mass may be stained by aniline of the desired color." 
Excellent results have been obtained by the use of carmine in 
coloring the mass for injecting the arteries, and Berlin blue or 
Prussian blue for the veins. 

METHOD OF INJECTION. 

Material. — A good brass syringe, if it can be had; a white metal syringe 
does fairly well. Injection mass as described above. Strong thread. Cat. 
Chloroform. Small sponge. Large jar. 

Kill a cat or rabbit with ether or chloroform by putting the 
animal into a tight box or jar with a sponge containing a teaspoon- 
ful of the anesthetic. When the animal is dead, open the thorax 
by cutting across the posterior end of the breastbone, and 



42 PHYSIOLOGY. 

through the costal cartilages on each side, being careful not to cut 
the mammary artery which runs along the inside of the breast- 
bone on each side. The mammary artery should be ligatured 
just under the anterior end of the breastbone. Now cut away 
the breastbone. The breastbone may be simply turned forward, 
and in this case it will not be necessary to ligature the arteries. 

Find the aorta and clear away any tissues that may obscure its 
base. Pass a ligature under the aorta here, but do not tie until 
the cannula is inserted. Cut a small slit in the apex of the left 

ventricle. Have in readiness sev- 
eral cannulas (or nozzles of a brass 
syringe) of different sizes, made by 
drawing out glass tubing. Each 
cannula should have a distinct neck, 

s^o^TKnot. so that [t ma y be tied in firml y- 

Insert the cannula through the 
ventricle into the base of the aorta. Now tie the cannula firmly 
by the surgeon's knot, made by crossing the two ends of the thread 
twice instead of once as in the ordinary knot ; draw firm with a 
slight sawing motion, but do not tie again. (See Fig. 3.) 

Inject with slow and steady pressure. Open the abdomen and 
watch the filling of the branches of the mesenteric artery. When 
they are well filled, tie the base of the aorta and remove the 
syringe. 




CHAPTER VI. 

THE BLOOD. 

A DROP OF FROG'S BLOOD. 

Material. — Live frog. Chloroform. 

i. Kill the frog as directed on p. 9. If blood enough is not 
obtained from the wound already made, open the body cavity and 
cut across the heart. Place a small drop of blood on each of sev- 
eral slides and quickly cover with cover slips. Examine first with 
a low and then with a high power. 

2. The colored corpuscles; elliptical in outline and with a faint 
yellowish pink tint. An edgewise view shows them to be flat- 
tened, with a bulging center caused by the nucleus. 

3. The colorless corpuscles ; smaller than the colored corpuscles, 
fewer, paler, and with a dotted appearance. They are spherical, 
hence present a circular outline. If watched closely for some time, 
they may be seen to change their shape. Make drawings at inter- 
vals of ten seconds. 

4. The clear spaces between the corpuscles are filled with the 
liquid part of the blood, called plasma. 

A DROP OF HUMAN BLOOD. 

Material. — A medium-sized needle, new and clean. Just before using, 
sterilize the point by passing it through the flame of an alcohol lamp or 
Bunsen burner. String, a foot long. 

1. To get a drop of blood from the finger, wind a cord around 
the finger, beginning at the base, drawing the cord moderately 
tight, until the last joint is reached. By this time the tip of the 

43 



44 PHYSIOLOGY. 

finger is usually well distended with blood. With a sterilized 
needle make a quick, sharp, light puncture near the base of the 
nail. This ordinarily brings a small amount of blood. Put a very 
small drop of blood on each of several slides and quickly cover 
with cover slips. 

2. Examine with a high power. The bulk of the bodies seen 
are the colored corpuscles. They are often called the red corpus- 
cles. But while in the mass they give the blood a red appearance, 
individually they are faint yellowish red. They are coin-shaped, 
being circular disks, hollowed in on each side. They often gather 
together, side by side, like a roll of coins. They have no nuclei. 

3. In the open spaces between the rolls of colored corpuscles 
there may occasionally be found some of the colorless corpuscles. 
They are usually called the white corpuscles. They often appear 
dotted, but it is not always easy to distinguish them from the 
colored corpuscles, since both have about the same diameter. 

4. The blood is composed of a clear liquid, the plasma, and 
the corpuscles. In the drop of blood examined under the micro- 
scope the plasma occupies the clear space between the corpuscles. 
The corpuscles make up one third of the bulk of the blood and 
the plasma the other two thirds. 

COAGULATION OF A DROP OF BLOOD. 

Material. — A medium-sized needle, new and clean. Sterilize the needle 
before using it. Piece of string a foot long. 

i. Wind the string rather tightly about the forefinger of the 
left hand, beginning at the base. When the end of the finger is 
reddened and distended with blood, make a quick, light puncture 
near the base of the nail. 

2. Remove the string and watch the drop of blood. Note that 
at first it is perfectly liquid. Later it becomes jellylike, i.e. it 
coagulates. Later still, observe that a clear, or slightly yellowish 
liquid oozes from it. This is the serum. What is left is the clot. 
After the serum has evaporated^ the clot dries and forms a scab. 



THE BLOOD. 45 

COAGULATION OF BLOOD. 

Material. — A live cat. Two ounces of chloroform. Two clean glass 
tumblers. A stirring brush made as follows : Handle, a piece of wood four 
inches long, half an inch wide, one fourth of an inch thick; for the brush take 
a piece of common wire window-screening, six inches long and three inches 
wide; wrap the screen tightly around one end of the handle, so that it projects 
an inch and a half beyond the wood. Small sponge. An assistant will be 
needed in this work. 

i. Place the cat under a large glass jar, crock, or wash bowl. 
Introduce a sponge soaked with the chloroform. Hold the jar 
firmly till the animal is quiet. 

2. After the animal has been quiet for at least five minutes, take 
it out and at once open the chest cavity by cutting away the breast- 
bone and the cartilaginous parts of the ribs. 

3. Lay the animal on two thicknesses of heavy paper, with the 
ventral margin of the chest at the edge of the table. Place a waste 
pail under the edge of the table. Have the assistant ready with 
a tumbler in the left hand and the stirring brush in the right, to 
catch and stir the blood as soon as it is caught. With the left 
hand pull the heart out so that it projects over the edge of the 
table. With the scissors make a quick cut into the right ventricle. 
Hold the tumbler tipped a little to one side, and stir the blood 
actively from the time the first blood touches the bottom of the 
tumbler. Half an inch of blood is enough. Whip as though 
whipping white of egg. Continue whipping for at least five min- 
utes. The threadlike matter that gathers on the wire is fibrin. 
If the stirring has been thoroughly done, the blood will no longer 
clot. What is the color of the whipped blood ? Why? 

4. As soon as the assistant takes the first tumbler away, a second 
tumbler should catch the rest of the blood that will flow out. If 
it does not flow freely, pressure on the abdomen may aid the flow. 
Let this blood stand undisturbed. Before presenting it to the 
class, the upper part of the tumblers should be cleaned by wiping 
them with a moist cloth, but no water should be allowed to drip on 
the blood. Watch closely the changes that take place in the 



46 PHYSIOLOGY. 

second tumbler. At least four stages should be distinguished : 
(i) the perfectly liquid blood; (2) the coagulated or clotted 
blood; (3) the separation of serum, a watery liquid; (4) the 
loosening of the clot till it is free in the serum. 

5. Thoroughly rinse the stirring brush till the fibrin appears 
white. Pull the fibrin to show its elasticity. Keep the brush in a 
tumbler of water. Keep all three tumblers under observation for 
two days. Does the whipped blood clot? Compare the colors of 
the blood in the two tumblers. Why the difference? 

6. After the defibrinated blood has stood for some time, pour 
half of it into a bottle, cork it, and shake it actively. Compare its 
color with that of the half remaining in the tumbler. Explain the 
difference. 



CHAPTER VII. 
RESPIRATION. 

THE RATE OF RESPIRATION. 

i. Count the respirations for one minute in a person sitting 
quiet. Repeat twice and take the average of the three. It is 
better to count the respirations in another person, because when 
one gives his attention closely to the process, the rate is likely to 
be modified. 

2. Count the respirations of a person who has been actively 
exercising, as running upstairs, or playing tennis, baseball, etc. 

3. Count the respirations of one who is lying down, but not 
asleep. Count again when the same person is asleep. 

4. Count the respirations before and just after a meal. 

5. Compare the rate of respiration in different individuals who 
are apparently in the same condition as regards exercise, mental 
excitement, eating, etc. 

6. Does the rate vary with age ? 

EXPERIMENTS ILLUSTRATING THE MECHANICAL PROCESS 
OF RESPIRATION. 

Material. — Bell jar with stopper, or large lamp chimney. Sheet rubber 
(rubber dam of the dentist), large enough to tie over the mouth of the jar or 
bottom of the chimney. Toy rubber balloon, or " squawker." Cork, rubber 
preferred, large enough to fit the neck of the jar, or the top of the chimney. 
Glass tube one foot long, size of a lead pencil. String, or rubber band. 
Marble, or collar button. Cork borer. 

Preparation. — Lay the marble on the center of the sheet of 
rubber, double the rubber over it, stretching the rubber strongly 
over the marble, and tie the marble firmly in place. Stretch the 

47 



48 PHYSIOLOGY. 

sheet of rubber over the mouth of the jar, or lamp chimney, with 
the projection made by the marble on the outside, and fasten 
with string or a rubber band. Bore a hole in the cork and fix the 
glass tube snugly in it, so that the lower end of the tube will ex- 
tend about halfway down the jar. Tie the balloon on the lower 
end of the glass tube. If a bell jar is not at hand, a large lamp 
chimney serves very well. A quart bottle may be used after cut- 
ting off the bottom as follows : File a deep notch across near the 
bottom ; heat an iron rod and apply one end of it to one end of 
the notch and slowly draw the rod around to the other end of 
the notch. The rod may need to be reheated. After cracking 
off the bottom of the bottle, file the edges so they will not cut 
the rubber. A collar button may be used instead of a marble. 
Or both may be omitted, and the action of the diaphragm shown 
by pressing it down on a ball or the bottom of a teacup. 

i. Inflate the balloon. Consider that it requires some expendi- 
ture of energy to do this. When the mouth is taken away from 
the tube, the balloon immediately collapses. 

2. Insert the balloon and tube into the jar, but do not cork, 
and repeat experiment i. The same results as before are 
noticed, and you can prove by sight, feeling, and hearing that 
when the balloon is inflated, some air comes out of the jar around 
the tube, and when the balloon collapses air again enters. 

3. Again inflate the balloon, and while it is inflated, tightly cork 
the jar. If the parts fit well, the balloon should now remain in- 
flated. This may, at first, seem strange, as the mouth is taken 
away and the tube is left entirely open to the air. But it will be 
seen that to just the extent that the balloon contracts, so much 
more space is left in the jar outside of the balloon. This means 
diminished pressure, and the pressure of the outside air, remain- 
ing the same as before, presses the diaphragm up and keeps the 
balloon distended, maintaining equilibrium. 

4. Pull the diaphragm down, using the marble as a handle. 
This shows the expansion of the lung by the pressure of the 
external air when more space is given by the depression of the 



RESPIRATION. 49 

diaphragm. On releasing the diaphragm, it springs upward, and 
the balloon becomes reduced in size, driving out part of the air 
that was in it. This shows how expiration is accomplished, so 
far as the diaphragm is concerned. 

5. Make a drawing showing the position of the parts in 
inspiration and another showing the position of the parts in 
expiration. 

ACTION OF THE CHEST WALLS IN RESPIRATION. 

Material. — Hand bellows. Toy balloon, or "squawker." Rubber stopper, 
to fit the nozzle of the bellows. Glass tube, eighteen inches long, of the 
diameter of a lead pencil. Piece of window glass three inches square. 

i. Work the bellows. While separating the handles air enters 
through the hole in the side past the valve. On bringing the 
handles together the air is under pressure and tries to escape 
everywhere. It closes the valve where it entered and escapes 
through the nozzle, the only opening left. 

2. Cut a hole, two or three inches square, at the place of the 
hole on the side. Fit in the glass, air tight. Now on working 
the bellows, the air enters the nozzle when the handles are 
separated, and passes out through the nozzle when the handles 
are brought together. 

3. Cut off the nozzle to a point where the cork can be used, 
say where it is about an inch in diameter. Bore a hole through 
the cork and fix the glass tube tightly in it, so that the inner end 
of the tube will come opposite the glass window. Tie the balloon 
on the end of the tube and fit the cork snugly in the nozzle. 

4. Separate the handles. Explain why the balloon now be- 
comes inflated. What phase of respiration is represented? 

5. Bring the handles together. Explain why the balloon 
collapses. What phase of respiration is here represented? 

ILLUSTRATION OF THE MINUTE STRUCTURE OF THE LUNG. 

Material. — A rubber balloon. Glass tube three inches long, of the 
diameter of a lead pencil. Three pieces of white rubber tubing, each three 



50 PHYSIOLOGY. 

inches long, same size as the glass tube. Dye one of these tubes ced, and one 
blue, in red and blue inks. Pinchcock, or clothespin. Bag of netting, three 
inches in diameter, one side dyed red, the other blue ; or a bag made of red 
and blue netting. 

i. Tie the balloon to one end of the glass tube. The balloon 
represents an air sac, or vesicle, of the lung. The glass tube corre- 
sponds to a bronchial twig, through which air enters the air sac. 

2. Slip the bag of red and blue netting over the balloon. The 
netting represents the capillaries which surround the air sac. 

3. Slip one end of the red and blue rubber tubes into the 
mouth of the bag of netting, each on the side of the bag having 
the same color. Tie the mouth of the bag down on the glass 
tube, catching the ends of colored tubes at the point where 
the balloon was tied to the glass tube. The blue tube represents 
a branch of the pulmonary artery, the red a branch of the pul- 
monary vein. 

4. Slip the piece of white rubber tube on the end of the glass 
tube. Inflate the balloon and shut the air in by the pinchcock 
or clothespin. 

5. Review: the balloon represents an air sac; the glass tube 
the bronchial twig through which the air enters and leaves the air 
sac ; the blue tube the pulmonary artery which brings the blood ; 
the netting the capillaries which distribute the blood around the 
air sac; the red tube represents the pulmonary vein through 
which the blood returns to the left auricle, after changing from 
blue to red. 

TO SHOW THE ACTION OF CILIUMS. 

Materials. — Live frog. Cork. Microscope, slide, and cover. Salt 
solution. Live clam. 

1. Kill a frog and destroy the brain and spinal cord, following 
directions on p. 9. Lay the frog on its back ; divide the lower 
jaw lengthwise and continue the cut as far as the stomach. Pin 
out the flaps at the sides, thus laying bare the roof of the mouth 



RESPIRATION. 5 1 

and gullet. If the lining of the mouth seems dry, moisten it 
with the normal salt solution. Cut some cork fine, like sawdust, 
and sift a little of it on the roof of the mouth, between the eyes. 
The current of mucus, caused by the vibrations of the ciliums, 
carries the particles toward the stomach. 

2. Snip off a little of this ciliated lining, mount it in salt solution, 
and examine under a high power. The vibrations of the ciliums 
should be seen. A small piece of a clam's gill, mounted in the 
same way, usually shows the action of the ciliums. 

EXPERIMENT TO SHOW THAT THE EXPANSION OF THE LUNG 
IS DUE TO THE PRESSURE OF THE EXTERNAL AIR. 

Material. — Dead rabbit, with unpunctured thorax. 

1. Open the abdominal cavity and pull back the liver and 
stomach. Note the pink lungs resting against the thin dia- 
phragm, which is nearly transparent in the center. 

2. Pull the diaphragm back and observe that the lungs follow 
it, keeping in contact with it all the time. 

3. Lightly puncture the diaphragm on one side. Note that 
the air rushes in and that the lung collapses and recedes from the 
diaphragm. 

4. Observe that the other lung does not collapse, showing that 
the two lungs are separated by an air-tight partition. Now punc- 
ture the other side of the diaphragm. 

INFLATION OF THE LUNGS IN THE CHEST CAVITY. 

Material. — Dead rabbit, with unpunctured lungs. Glass tube as thick 
as a lead pencil, six inches long. Rubber tube, same size and length. 

1. Cut away the breastbone with the cartilages of the ribs. 
Note that the lungs are collapsed and lie in the dorsal part of the 
chest cavity. 

2. In the middle of the throat cut down to the windpipe. 
Cut a slit in the windpipe and insert a glass tube, with a rubber 
tube on its outer end. 



§2 PHYSIOLOGY. 

3. Inflate the lungs. Note how they fill the chest cavity and 
surround the heart. Observe the change in the color of the lungs 
when inflated. Note also the lobes into which the lungs are 
divided ventrally. 

4. The pointed anterior end of # a lung is its apex. The large, 
posterior end is its base. Note how the bases of the lungs fit 
against the diaphragm. 



STUDY OF SPECIAL FORMS OF RESPIRATION. 

1. Perform the act of coughing. Is it an inspiration or an 
expiration ? Does the air pass out through the mouth or through 
the nose ? Place the hand on the front of the abdomen, while 
coughing forcibly. Can you detect muscular action ? What is 
the object of coughing ? 

2. Repeat the above experiments with sneezing, sniffing, hic- 
cuping, yawning, sighing, drinking, gargling, hawking, snoring, etc. 
Use a mirror to learn the positions of the organs in the back of 
the mouth. 

3. Study also the action in laughing, crying, sobbing, sucking, 
choking, spitting, smoking, whistling, blowing, panting, hissing, 
chirping, clucking, grunting, snorting (of animals), etc. Classify 
all these special forms of respiration. 

4. Try to breathe abdominally, i.e. by means of the diaphragm 
alone, letting the chest remain passive. 

5. Try to breathe by means of the chest alone, with the dia- 
phragm inactive. 

CAPACITY OF THE LUNGS. 

Have the class stand and each hold the right hand up to about 
the level of the shoulder with the elbow near the side. 

1. Let all breathe together at about the ordinary rate and depth, 
and let the hand rise about three inches during inspiration and 
sink again during expiration. The amount of air taken in and 



RESPIRATION. 53 

sent out at an ordinary breath is from 20 to 30 cubic inches. This 
is called the tidal air. 

2. As before, let the hand go up and down with the breathing, 
but at the end of the third inspiration, instead of stopping with the 
usual amount, keep on breathing in as much as possible, letting 
the hand rise accordingly. This extra amount of air that can be 
taken in above the ordinary breath is called the complemental air. 
It is estimated to be, on the average, about 120 cubic inches. 

3. Begin as before and, at what would be the end of the third 
expiration, continue to breath out as much air as possible, indicat- 
ing the degree by correspondingly lowering the hand. This air 
that can be breathed out beyond the ordinary expiration is called 
the reserve air. It is estimated at about too cubic inches. 

4. The air cannot all be breathed out. The remainder is called 
the residual air, and is computed to be about 100 cubic inches. 

5. All the air that can be breathed out after a full inspiration, 
i.e. the sum of the complemental^ tidal, and reserve air, is the 
measure of the vital capacity, and is estimated to be, on the aver- 
age, from 240 to 250 cubic inches. 

MEASUREMENT OF EXPIRED AIR. 

Apparatus. — A gallon bottle. A rubber tube one fourth of an inch in 
diameter, eighteen inches long. Pint measure. Three-cornered file. 

i. Pour a pint of water into the bottle and mark its level 
with the file. Repeat till the bottle is full. 

2. Fill the bottle with water, place the hand over the hole, and 
invert it in a basin of water. Breathe into the bottle through 
the rubber tube. How much do you breathe out at an ordinary 
breath ? How much can you breathe out after an ordinary 
inspiration ? How much can you breathe out after the fullest 
inspiration ? Can you, by practice, increase your lung capacity ? 

3. Is inspired air of the same temperature as expired air? 
Does inspired air have the same volume as expired air? Does 
the expired carbon dioxid equal the volume of retained oxygen? 



54 PHYSIOLOGY. 

EXPANSION OF THE CHEST. 

Apparatus. — Tape measure. 

i. Measure the circumference of the chest, a little below the 
armpits, during ordinary quiet breathing. 

2. Get the circumference after taking in as much air as possible. 

3. Measure after expelling as much air as possible. 

4. Practice frequently for a week to see if the range of expan- 
sion can be increased. 

EXPERIMENTS ILLUSTRATING THE CHEMISTRY OF 
COMBUSTION. 

Material. — Large pudding pan or basin. Several quart fruit jars. Piece 
of phosphorus, size of a pea. Chalk crayon. Strip of sheet lead, one inch 
wide, eight inches long. Fine wire one foot long. Pail of water. Tin cup. 
Matches. Lime water prepared the day before by putting a piece of quick- 
lime about the size of a hen's egg into a quart of water; pour off the clear 
liquid from the top of the jar for experiment. Wooden splinters. Three 
clean tumblers. Two horse-radish bottles. A quart jar and a horse-radish 
bottle each full of oxygen. Two horse-radish bottles full of carbon dioxid. 
Short pieces of Christmas-tree candles. One foot of soft wire, size No. 18. 
One foot of picture cord (braided wire). Six inches of magnesium ribbon. 
Pair of bellows. Two ounces of sulphuric acid, chemically pure. Thermometer. 
Pipette, with large bulb. Apparatus for generating oxygen and carbon dioxid 
(consult any chemistry). Glass tube, three sixteenths of an inch in diameter, 
one foot long. 

Caution. — Always handle phosphorus with forceps, never with 
the fingers. Cut it under water, in a plate or basin. Take care 
not to leave any pieces on the table or floor. 

Preparation. — Hollow out the large end of a crayon, and wire 
it to one end of the strip of lead. Bend the strip so that the crayon 
cup will be held at about one third of the hight of the jar, and 
set it in the basin. Lay the piece of phosphorus in the hollow in 
the crayon. Pour about two inches of water into the basin. 

1. Ignite the phosphorus and lower an inverted quart jar over it. 
Do not let the fumes escape into the air. Keep the mouth of the 



RESPIRATION. 55 

jar covered with water, adding water to make up for what is drawn 
up into the jar. 

Explanation. — The phosphorus in burning unites with the 
oxygen of the air, forming a white cloud of oxid of phosphorus. 
This is gradually absorbed by the water, and the pressure of the 
outside air pushes water up into the jar to take the place of the 
oxygen that has been condensed in uniting with the phosphorus. 
After the cloud has disappeared, the remaining clear gas is nitrogen. 
What part of the air is nitrogen ? What per cent of air is oxygen ? 

2. After the nitrogen has become clear, lift the basin and jar 
and lower them carefully into water in a pail or sink until the 
mouth of the jar is well under the water. Hold the jar and let the 
basin go. Slip the palm of the hand over the mouth of the jar and 
set it right side up on the table, holding firmly to retain the nitro- 
gen. Light a taper and slowly lower it into the nitrogen. Quickly 
cover the jar again and repeat the experiment. Nitrogen does 
not support combustion. Neither will it support life. An animal 
would soon die in nitrogen, not because it is poisonous, but simply 
because it does not support life. 

3. Into a small jar or horse-radish bottle of oxygen lower a 
splinter with a live coal at the end (left after blowing out the 
flame). The coal is kindled into flame. This shows the chief 
characteristic of oxygen, that is, its power of supporting fire. 

4. Into a small jar of carbon dioxid lower a lighted taper. It 
is at once extinguished. 

5. Into a small jar or bottle of carbon dioxid pour a little lime 
water and shake vigorously, holding one hand over the top of the 
jar. The test of carbon dioxid is that it turns lime water milky. 

6. Pour a little lime water into a tumbler, and breathe through 
it by means of a glass tube. If the lime water turns milky, it shows 
the presence of carbon dioxid in the breath. 

7. Invert a jar over a burning candle. The light is soon extin- 
guished. Pour a little lime water into the jar and shake actively. 
Is carbon dioxid produced by the burning candle ? The oxygen of 
the air unites with the carbon of the candle, forming carbon dioxid. 



56 PHYSIOLOGY. 

8. Over a burning candle invert a clean, cold tumbler. A film 
of moisture is seen on the inside of the tumbler. This water vapor 
was produced by the burning of the candle. 

9. Breathe into a cold tumbler. The moisture from the breath 
is condensed on the inside. 

10. Burn a piece of picture cord in oxygen. First heat one 
end red hot in a Bunsen flame or in alcohol flame, dip it into 
powdered sulphur, and, when this is burning actively, lower it into 
a quart jar of oxygen. Hold the wire to one side, and loosely 
cover the jar with a piece of tin or thin board. The only 
product of burning iron is iron oxid, formed by the union of iron 
and oxygen. 

n. Place a short piece of the picture cord in a tumbler of 
water. In a few days it will show that it has rusted. This rust is 
iron oxid, essentially the same as the iron oxid formed by burning 
the iron. In this case it has oxidized (united with oxygen) slowly ; 
when it was burned it oxidized rapidly. One of these processes 
we call combustion ; the other is called rusting. Both are 
examples of oxidation. 

12. Burn three inches of magnesium ribbon, holding it with 
forceps. It gives an intense white light ; after the first glance 
turn the head away, as the intense light is bad for the eyes. The 
only product is the white ashes, magnesium oxid, formed by the 
union of oxygen and magnesium. 

13. Scrape a short piece of magnesium ribbon till it is bright 
and place it in a tumbler of water. The tarnish that forms on it 
is the result of oxidizing. Oxygen unites with the magnesium to 
form magnesium oxid, as in the case of burning, only here the 
process is slow- and does not produce light nor any perceptible 
heat. We call the result magnesium rust. 

14. Fill a fruit jar with water and invert it in a basin of water. 
The jar should remain full of water. Exhale slowly through a 
rubber tube into the jar. Continue exhaling, but at the usual 
rate of breathing, till the jar is full. Be sure to leave no water in 
the jar. Carefully cap the jar and set it away in a warm place 



RESPIRATION. 57 

for a day or two. The bad odor comes from the putrefaction of 
the organic matter thrown out in the expired breath. The or- 
ganic matter comes from the oxidation of the tissues as a result of 
their activity. 

15. Hold a thermometer at arm's length. It indicates the 
temperature of the air that you are breathing in. Breathe for a 
few minutes upon the bulb of the thermometer. What is the tem- 
perature of the expired breath as compared with the inspired 
air? These experiments show that breathed air has gained 
(a) heat ; (p) water vapor ; (c) carbon dioxid ; (d) waste products, 
or impurities, having no definite name, often called by the gen- 
eral name " organic waste matter." They are highly putrescible. 

16. With a pair of bellows force the air of the room through a 
small quantity of lime water. By continuing this process it may 
be shown that the air contains carbon dioxid. Does it contain as 
much as the expired breath? 

1 7. Exhale for a long time through a small quantity of sulphuric 
~acid (chemically pure), using a large pipette with a large bulb. 
Be very careful not to suck up any of the acid. The acid will in 
time grow dark colored, indicating the presence of organic matter. 

THE GASES IN LIQUIDS. 

Material. — Fresh blood. Air pump. Two tumblers. 

1. Place a tumbler of water under the receiver of an air pump 
and exhaust the air. What do you see ? 

2. Place a tumbler, partly filled with freshly drawn blood, 
under the receiver of an air pump and exhaust the air. Is there 
any change in the blood ? 

ILLUSTRATION OF THE CHANGES IN THE COLOR OF THE 

BLOOD. 

Material. — A pluck (sheep, pig, or calf). Apparatus used to show the 
action of the heart. (See p. 29.) One quart of strong litmus solution, neu- 
tralized or slightly alkaline. Two small sponges. Ammonia. Hydrochloric 



58 PHYSIOLOGY. 

acid. This experiment is solely to illustrate the changes in the color of the 
blood. The blood contains nothing like the acid and ammonia. 

i. Prepare the heart and connect it with the apparatus as 
directed on p. 29. Fill the heart with the litmus solution. Place 
a sponge in the throat of each funnel. Work the heart till each 
sponge is saturated. 

2. Pour ammonia on the sponge in the funnel representing the 
capillaries of the body. On the sponge in the funnel that repre- 
sents the capillaries of the lungs pour hydrochloric acid. 

3. Now on working the heart the liquid should turn blue as it 
runs through the funnel representing the capillaries of the body. 
It should turn red as it passes through the other funnel, which 
represents the capillaries of the lungs. It will require some prac- 
tice to determine how much of the liquids is needed. 

4. To make these changes continuous it will be necessary to 
add a little ammonia and hydrochloric acid from time to time, as 
needed. 

THE TEMPERATURE OF THE BODY. 
Apparatus. — A clinical thermometer. 

1. Insert the thermometer into the mouth, well back under the 
tongue. Keep it there about four minutes. Try this with dif- 
ferent persons, carefully rinsing the thermometer. Get the aver- 
age of a large number of observations. 

2. Get the temperature of the same person before and after 
exercise, before and after eating, on rising in the morning and on 
going to bed at night, etc. 

3. Take the temperature on a hot day and again on a cold day. 

4. Take the temperatures of persons of different ages, from 
children to the aged. 

5. What is the temperature during fever? 

6. What is the temperature during a chill ? 



CHAPTER VIII. 

VENTILATION AND HEATING. 

VARIATIONS IN TEMPERATURE OF DIFFERENT PARTS OF A 
HEATED ROOM. 

Apparatus. — Thermometer. Step ladder. 

i. Carry a thermometer to various parts of the room and 
hold it in each place long enough for the thermometer to be 
affected. 

2. Hold the thermometer (a) just over, or very near, the 
source of heat ; (&) at half the hight of the room over the source 
of heat ; (V) at the ceiling over the same point. 

3. In the middle of the room (a) at the floor; (&) at half the 
hight of the room ; (c) at the ceiling. 

4. Along the wall opposite to the source of heat (#) at the 
floor ; (&) halfway up ; (V) at the ceiling. 

5. Compare the outside and inside walls of a room at the three 
hights indicated, especially near windows. 

6. At what hight and in what part of the room, especially a 
schoolroom, is it best to hang a thermometer for general use? 

AIR CURRENTS IN A HEATED ROOM. 

Material. — Sticks of punk used in touching off fireworks; or joss sticks. 
These are on sale at toy stores. If these cannot be obtained, use touch paper, 
prepared by soaking straw-paper in a solution of potassium nitrate. After 
drying the paper, cut it into strips half an inch wide. 

i. Hold a stick of burning punk just over the source of heat, 
whether stove, register, or radiator. Which way does the smoke 
go? Repeat at different hights in various parts of the room. 

59 



60 PHYSIOLOGY. 

2. Test with smoke any currents at each register or ventilating 
flue in the room. 

3. Test for currents near the closed windows, from top to 
bottom. 

4. Test in the same way at the top and bottom of the doors. 

5. Open a window two inches at top and at bottom. Test for 
currents (a) at the top ; (b) at the bottom ; (c) at the opening 
between the upper and lower sashes. 

6. If the fan system is used, test for air currents in about the 
same way, in various parts of the room. 

AMOUNT OF CARBON DIOXID IN DIFFERENT PARTS OF A 

ROOM. 

Apparatus. — Bellows. Step ladder. Lime water. Two-ounce bottle. 
Rubber tube, one foot long, to fit on the nozzle of the bellows. 

1. Half fill the bottle with lime water. At the floor, near the 
source of heat, force air through the lime water, keeping the end 
of the tube at the bottom of the bottle. Work the bellows with a 
full, steady stroke. Count the strokes till the water is noticeably 
milky. 

2. Empty the bottle and rinse it. With the same amount of 
lime water, repeat the experiment at half the hight of the room, 
over the same point. Try to work the bellows at the same rate 
and with the same force, as before. Count the strokes till the 
lime water becomes of the same degree of milkiness as before. 
Compare the number of strokes. 

3. Repeat at the ceiling over the same point. 

4. Repeat at the three hights in various parts of the room. 
In different rooms. 

5. Perform these experiments in a schoolroom just after school 
begins. Perform them again just before school is dismissed at 
noon. Compare results. 

6. If possible, use the more expensive and more accurate 
apparatus for testing the amount of carbon dioxid in the air. 



VENTILATION AND HEATING. 61 

DUST. 

i. Gather a pailful of clean snow and melt it. Is the water 
that is formed pure and clear? 

2. Take a dry clod from the street. Hold it up and drop it. 
Pulverize the same clod and drop it from the same hight. Does 
it fall as quickly as before ? 

3. On a sunny day nearly close the shutters or curtains, till 
only a few beams of sunshine enter the room. Near these streaks 
of sunshine, shake various cloths and garments, such as woolen 
and cotton underwear, handkerchiefs, napkins, towels, blankets, 
rugs, etc. What is the source of the dust given off? Is it matter 
that has fallen on the cloth, or does it come from the fabric 
itself? 

4. Compare the common broom with the patent carpet sweeper 
in these respects : (a) the extent to which they remove dust and 
dirt from the carpet ; (J?) the amount of dust sent into the air ; 
(V) the rate of wear on the carpet ; (d) the ease and comfort with 
which they are used. 

5. Why is it likely to be dusty indoors when it is muddy out- 
doors ? 

6. Which becomes dusty sooner, a paved street or an unpaved 
street? Why? 

7. Why do janitors sometimes use damp sawdust in sweeping? 

8. Are any special liquids used to prevent dust in school- 
rooms? 

9. What months are worst for hay- fever patients? Why? 

10. What are the best ways to keep dust, and dust-making 
matter, out of a house ? 

11. What are the best ways to avoid making dust in a house? 

12. What are the best means of getting rid of dust that is in a 
house ? 

13. Cars are sometimes cleaned by forcing air through a rubber 
hose, with a nozzle. What advantage has such a system ? What 
disadvantages ? 



62 PHYSIOLOGY. 

14. Another method now used in cities for cleaning carpets 
uses also the long rubber hose, but replaces the nozzle by a funnel ; 
instead of forcing air out, a suction pump draws air in through the 
funnel. The funnel is slowly moved about, over all the surface to 
be cleaned, sucking up the dust. How does this "vacuum" 
system compare with that mentioned in No. 13? 

15. In what season, or outdoor condition, is the least dust, or 
dust-making material, brought into houses from outdoors? 

16. In how many ways does street sprinkling favor comfort and 
health? 

1 7. After the sod has been worn off, what different factors con- 
tribute to the constant deepening of a path ? 

18. Does the use of bicycles and automobiles have any effect on 
the amount of dust made, or stirred up ? 

19. What part of your state is dustiest ? What part least 
dusty? 

20. What are some of the advantages of traveling by boat? 

21. Aside from hair and dandruff, what are the principal 
materials that accumulate in a hair brush? What are their 
sources ? 

22. Why are the walls more likely to become soiled over radi- 
ators and registers ? 

23. Which is more cleanly, gas or electric light? Why? 

24. For upholstering furniture, how does plush compare with 
leather, or leatherette, so far as dust is concerned ? 

25. Which is likely to contain more dust, a carpeted room, or 
one in which rugs are used on a hard-wood or linoleum-covered 
floor? 



CHAPTER IX. 

EXCRETION. 

STUDY OF THE SKIN OF THE HAND. 

Material. — Lens, linen tester preferred. An ink pad, such as is used 
with rubber stamp outfits. Or spread mimeograph ink on a slate or piece of 
glass. Fine needle. 

i. Place the tips of the fingers on the back of the hand. See 
how far you can make the skin slip forth and back. Pinch up a 
fold of skin on the back of the hand. How far can you pull it 
out? Test the skin of the palm in the same way. 

2. Pinch up folds of skin on various parts of the body. Note 
the variation in thickness and mobility. 

3. Are the large veins of the hand in the skin or under it? 
Are there blood tubes in the skin? 

4. Note the ridges on the palm of the hand. Study their 
arrangement, first with the naked eye, later with the aid of a 
lens. 

5. Press the inner surface of the first joint of the right forefinger 
on the ink pad or on mimeograph ink, and then on clean white 
paper. Compare the finger prints (of the right forefinger) of all 
the members of a class. Compare the thumb prints in the same 
way. 

6. Run a fine needle along in the outer layer of the skin of the 
palm. Does it give pain? Does it draw blood? Repeat with 
other parts of the hand. 

7. When you have a water blister or a blood blister, insert a 
needle and draw off the liquid. How much of the skin is outside 
of the blister and how much is beneath it? What is this liquid ? 
How does the liquid get into this space? Why does it remain 

63 



64 PHYSIOLOGY. 

there ? What would have become of it if you had not removed 
it? What makes the space? 

8. What is a black-and-blue spot? 

9. With the tip of the finger press firmly on the back of the 
hand. On removing the finger, what color do you see ? Does this 
color remain? Explain. 

10. Place a linen tester on the palm of the hand. Note the 
sweat pores, or openings of the ducts of the sweat glands. Count 
the pores within the square thus seen. Measure the square and 
estimate the number of sweat glands in a square inch of the palm. 

THE STRUCTURE OF THE SKIN. 

Material. — Prepared slides, showing cross sections of the skin. Live 
frogs. Rubber tube, one foot long, one eighth of an inch in diameter. 
Insulated electric bell wire, red, one foot long. Model of the skin. 

i. Examine a cross section of the skin with a low-power objec- 
tive. Note two layers of the skin : {a) the outer layer, or epider- 
mis : (b) the inner layer, or dermis. 

2. With a high power study closely the cells of the epidermis. 
Note how they change in shape from the inner to the outer 
layer. 

3. Note the more fibrous structure of the dermis. The eleva- 
tions of the dermis that extend into the epidermis are the papillas. 

4. The sweat glands; note the cut ends and partial coils. 
Remember that the section you are studying is a very thin slice 
across the skin, and that no one section can show all of the gland 
any more than one board can show all of a winding hole through 
the log from which the board was sawed. In connection with the 
examination of this section, read a description and look at a model 
or drawing of a sweat gland. Examine a number of sections and 
study all parts of sweat glands that are shown. 

5. The hairs. If hairs are present in the section, note where 
the hairs start. Describe the root of a hair. Do hairs grow out 
at a right angle to the surface of the skin ? 



EXCRETION. 65 

6. Note the oil glands and their relations to the hairs. 

7. Model of a sweat gland. Take a small rubber tube about 
a foot long. Close one end. Tie the half with the closed end 
into a globular knot. Around and between the coils, wind a red 
insulated electric bell wire to represent the capillaries. The two 
ends of the wire should be free to represent the blood tube 
supplying the blood and the tube which carries it away. 

8. Wash the hands in warm water. Wipe them fairly dry. 
While they are still somewhat moist, rub the palms together. The 
little rolls that appear are composed of the dead cells of the epi- 
dermis. Put a tiny bit of this material in a drop of water on a 
slide and examine under a high-power objective. 

9. Mount a frog on a board as directed on p. 34. Examine 
the web with a low power. The blood tubes are all in the dermis, 
or deeper layer of the skin. Note the dark pigment bodies. Do 
they change their form? To what is the frog's color due ? 

10. Select two frogs of about the same color. Keep one in a 
dark place for an hour or 'two. Keep the other in bright light. 
How do they now compare in color ? Examine the pigment bodies 
of the two. How do they differ? 

11. What is tattooing? What materials and what instruments 
are used? Is the result permanent? Why? How does a tattoo 
mark differ from a black-and-blue spot? 

12. What change is wrought in the skin when one becomes 
tanned? What are freckles? 

THE WAYS IN WHICH BODIES GIVE OFF HEAT. 

Material. — Hot potato. Plate. String. Wet bulb thermometer, or 
ordinary thermometer, and small piece of cheese cloth. Alcohol or gasoline. 

I. Radiation. Hang a hot potato by a string. Hold the hand 
two inches above, below, and in all directions from it, with the 
palm toward it. Do you feel the heat given off? The potato 
radiates heat in all directions. Hold a book or a plate between 
the potato and the hand. Do you now feel the heat? 



66 PHYSIOLOGY. 

2. Conduction. Lay the potato on a cold plate. Touch the 
potato. It warms your hand by conduction. Does the plate get 
warmer? Communication of heat by contact is called conduction. 

3. Convection. Lay a hot peeled potato on a plate. The cloud 
of so-called " steam " arising from it is water, carried upward by 
the rising current of air. The air in contact with the potato is 
heated. It then rises, and cold air takes its place. Thus a cur- 
rent is kept up, and heat is gradually taken from the potato by 
convection. 

4. Evaporation. If a wet-bulb thermometer is not at hand, 
wrap two thicknesses of cheese cloth around the bulb of a common 
thermometer. Note (a) the temperature when the cloth is dry; 
{b) dip the bulb into water that has the temperature of the room ; 
hold it there a few minutes and note the temperature ; (V) lift the 
thermometer out of the water and see if the mercury changes its 
level. The falling of the mercury shows that heat is taken from 
the bulb to evaporate the water from the cloth. Repeat the 
experiment, using alcohol or gasoline * instead of water. 

THE ACTION OF THE SKIN. 
Material. — Candy jar. Medicine dropper. Cologne or ether. 

1. Insensible perspiration. Hold up one hand and slip a candy 
jar over it. Wrap a towel or handkerchief around the wrist to 
close the mouth of the jar. Note the moisture that soon gathers 
on the inside of the jar, from the insensible sweat of the hand. 

2. What is the effect of keeping rubbers on the feet for a long 
time? Does the water from the inside pass out any more readily 
than water from the outside passes in? What is the effect of wear- 
ing high rubber boots? Of wearing rubber gloves? Is it well to 
wear rubber clothing of any kind for any length of time? Are 
there any garments that are impervious to water and, at the same 
time, pervious to air? 

3. Get your exact weight after breakfast, or just before going 
to school. Weigh again just before dinner. 



THE KIDNEY. 67 

4. Get your exact weight just before taking active exercise in a 
gymnasium. After an hour's vigorous work, weigh again. How 
much difference is there ? In all these experiments make proper 
allowance for any errors that may affect the results. 

5. Place a drop of cologne or ether on the back of the hand 
of each student, using a medicine dropper. Note two results : 
(a) it has a cooling effect ; (&) the liquid quickly disappears. 
What is the relation between these two facts? Carefully compare 
the results of this experiment with those of No. 4, p. 66. 

THE KIDNEY. 

DISSECTION OF THE KIDNEYS. 

Material. — Sheep kidneys, one for two students. It may be necessary 
to send to the nearest large city, though in smaller cities a number may be 
accumulated by getting all the butchers to save them for a week or two before- 
hand. Pigs' kidneys will serve. 

1. Observe the depression on one edge of the kidney. This is 
the hilum. 

2. From the hilum trace a slender white tube, the ureter, back 
to the bladder. Find also the renal artery, which brought the 
blood to the kidney, and the renal vein, which carries the blood 
away from the kidney. 

3. With a sharp scalpel split the kidney like a bean, beginning 
at the outer border, stopping when you reach the cavity with a 
white lining. With forceps pry about to explore the cavity thus 
laid open. Note the branches of the cavity into the kidney. Can 
you discover the blood tubes extending through these white 
branches to the outer part of the kidney? 

4. In the center of the white membrane lining the cavity find 
the opening of the'ureter, through which the urine is conveyed to 
the bladder. Pass a slender probe, such as a blunt wire, along the 
ureter. 

5. Note the difference in color of the outer and inner parts of 
the kidney. At the line of change of color find where the blood 



68 PHYSIOLOGY. 

tubes first branch into the real substance of the kidney. Carefully 
examine the cut surface of the kidney to see its markings. 

6. Make a drawing of one half of the kidney as seen from the 
inside. 

7. Cut across the middle of a kidney at right angles to its 
length and make a drawing of the cross section. The projection 
of kidney substance into the cavity, opposite the beginning of the 
ureter, is the urinary pyramid. From the apex of the pyramid, 
through many fine holes, the urine issues into the cavity of the 
kidney. From the cavity of the kidney it passes on to the 
bladder. 

MODEL ILLUSTRATING THE MINUTE STRUCTURE OF THE 

KIDNEY. 

Material. — Thistle tube. Piece of thin muslin three inches square. 
Thread. Insulated electric bell wire, red, one foot long. 

1. Lay the muslin oyer the mouth of the funnel of the thistle 
tube. Push it down to make a pocket within the funnel. Bend 
down the cloth around the edge of the funnel and tie it in place. 

2. Coil the electric bell wire into a fairly close knot, or ball, 
with the two ends projecting about two inches. 

3. Push the ball of wire down into the pocket in the funnel, 
with the ends projecting. 

4. The funnel with its pocket represents the urinary capsule ; 
the tube corresponds to the urinary tube, or tubule ; the knot of 
red wire corresponds to the tuft of capillaries contained within 
the urinary capsule. As the blood flows along in the tuft of 
capillaries, part of the water soaks out through the wall of the 
capillary, then through the inner layer of the capsule, and then 
passes along the urinary tube to the cavity of the kidney. 

5. There should also be a coil of red wire around the tube, to 
correspond to the capillaries that surround the urinary tube. 
It is thought that most of the water comes from the capillary tuft 
in the capsule, but that the urea, and perhaps the larger part of 
the real waste matter, passes into the urinary tube through its side. 



CHAPTER X. 
FOODS. 

THE FOODSTUFFS IN MILK. 

Material. — A tumbler of milk. Seamless tin cup or small seamless tin 
basin. Spoon. Stove, Bunsen burner, or alcohol lamp. Vinegar. 

i. Taste fresh milk. The sweet taste is due to the milk sugar 
in it. Milk sugar represents the carbohydrates, one of the five 
foodstuffs. 

2. Let the milk stand overnight. How much cream is there? 
Skim it off. The cream is an example of the fats, another class 
of foodstuffs. 

3. Add vinegar to the skimmed milk. The curdled part is 
casein. This is one form of proteid foodstuff. Strain through 
cheese cloth to separate the casein from the liquid. 

4. The bulk of the remaining liquid is water, which is one of 
the foodstuffs. How does the color now compare with the original 
color of the milk ? How do you explain this change in color ? 
What per cent of milk is water? 

5. Pour this watery remainder of the milk into a seamless tin 
cup or basin and boil dry. Has the dried residue any taste? 
Continue the heat till you burn what is left. The remains, or 
ashes, are the mineral matters, or salts. They represent another 
class of foodstuffs. 

6. Milk is a food, containing five foodstuffs ; (a) water ; (b) 
salts; (c) casein, a proteid; (d) cream, a fat; (e) sugar, a 
carbohydrate. 

7. Can you estimate the per cent weight of each of the five 
foodstuffs in milk? 

69 



70 PHYSIOLOGY. 

WATER IN FOODS. 

Material. — Beefsteak, four ounces ; bread, one loaf ; a potato ; a turnip; 
an apple. Rice, one cupful. Tin plates. Oven. Scales. 

i. Cut about four ounces of steak into narrow strips. Lay 
them on a tin plate and weigh carefully. Place in an oven till 
dry but not burnt. Weigh again. The reduction in weight is due 
to the loss of water. What per cent of steak is water? 

2. Take a loaf of bread and treat it in the same way. What 
per cent of bread is water ? 

3. In the same way dry a teacupful of rice. What per cent of 
water does it contain? 

4. Cut a potato into thin slices and treat as above. W T ater 
makes what per cent of potato ? 

5. Test turnip, apple, and other foods in the same manner. 

6. To what extent are dried, or desiccated, foods used? Are 
they in special demand by any special class of trade ? For any 
special uses? More in some parts of the world than in others? 
What advantages have dried foods ? What disadvantages ? 

CHARACTERISTICS OF PROTEIDS. 

Material. — An egg. Half pound of beefsteak. Half pint of milk. Cup 
of beans. Test tubes. Strong nitric acid. Strong ammonia. Alcohol lamp 
or Bunsen burner. Chemical thermometer. Beaker. Wide glass tube or 
lamp chimney. Parchment or parchment paper, four inches square. 

i. Effect of heat on egg albumen. Put two inches of white of 
egg into a test tube. Place a beaker of water over the flame of 
the lamp or Bunsen burner. Set a thermometer in the white of egg 
in the test tube. Hold the test tube in the beaker of water, 
stirring gently as the heat increases. When the white of egg 
thickens and hardens, it is said to coagulate. At what temperature 
does this take place? 

2. Does heat have this same effect on all proteids? Try milk, 
bean soup, gelatin, lean meat, etc. 



FOODS. 71 

3. Effect of nitric acid and ammonia on proteids. Put a piece 
of hard-boiled white of egg into a test tube and pour a little strong 
nitric acid on it. What change? Rinse with water and add a few 
drops of strong ammonia. What do you see ? Apply this test to 
other proteids, — meat, cheese, beans, onions, etc. 

4. Odor of burning proteids. Burn a piece of lean meat on a 
shovel on the coals. Is the odor peculiar ? In the same way test 
cheese, beans, eggs, gelatin, etc. 

5. Putrefaction of proteids. Keep a piece of steak in a warm 
place for a few days. Watch a pan of milk that stands in a warm 
place for a few days. Expose a dish of rich bean soup in the 
same way. Why do eggs "get bad"? These foods are largely 
proteid. Do bread, flour, sugar, sirup, or fat show the same ten- 
dency to " spoil " and give off such bad odors? 

6. Indiffusibility of egg albumen. Wet a piece of parchment 
or parchment paper. Tie it over the end of a glass tube, an inch or 
more wide. Put some raw white of egg into a saucer and cut it 
in all directions with sharp scissors, to break it up. Shake thor- 
oughly with water in a graduate or lemonade shaker. Pour some of 
this into the parchment tube and set it in a tumbler. Test the 
liquid that comes through the parchment. Does egg albumen pass 
through the parchment? 

FAT IN FOODS. 

Material. — Ground flaxseed, corn meal, white flour, whole wheat flour, 
pecans. Patty pans. Ether. Beaker. Glass funnel. Filter paper. Clean 
white paper. 

i. Place a teaspoonful of each of the above substances (crush 
the pecan meats) on a piece of clean white paper. Lay the 
papers on tin plates or patty pans. Set them in an oven or other 
warm place. Do you find evidences of the presence of oil ? 

2. Put into a beaker four tablespoonfuls of ground flaxseed. 
Add an equal amount of ether. ( Caution : do not perform this 
experiment in a room where there is any fire either in stove, lamp, 



72 PHYSIOLOGY. 

or burning gas ; the vapor is very explosive.) After half an hour 
filter and set the liquid in a window, or where a draft will aid the 
evaporation of the ether. What remains after the ether has evapo- 
rated ? 

3. Repeat experiment No. 2. with white flour, entire wheat 
flour, corn meal, rice, white of egg, yolk, cheese, etc. 

AN ARTIFICIAL EMULSION. 
Material. — Olive oil. White of egg. Test tubes. 

1. Pour half an inch of olive oil into a test tube. Add water till 
the test tube is half full. Note the relations of the oil and water. 
Hold the thumb tightly over the mouth of the test tube, and shake 
actively. What is the appearance, and what is the relation of the 
oil and water now? Let the tube stand. What happens? Repeat. 
Will the oil and water stay mixed? 

2. To the same test tube add half an inch of white of egg. 
Shake actively. How does the result differ from that of the pre- 
ceding experiment? This is an emulsion. Each drop of oil is 
supposed to have a thin layer of white of egg around it which keeps 
it from separating so quickly from the water. 

A NATURAL EMULSION, — MILK. 

Material. — Half a test tube of rich milk. Slide and cover slip. Dilute 
caustic soda. Osmic acid. Medicine dropper. 

1. Mount a drop of rich milk on a slide, cover with cover slip, 
and examine under a high power. Note the fat globules. 

2. Place a drop of weak caustic soda on the slide at one edge 
of the cover slip. How are the fat globules affected ? 

3. Mount another drop of milk and run a drop of osmic acid 
under the cover. How does this affect the fat globules? 

4. In making butter the churning breaks away the thin coating 
of albumen around each of the fat globules and they run together, 
i.e. the butter " gathers." What is the food value of buttermilk ? 



FOODS. 73 



CARBOHYDRATES. 

A. STARCH. 

THE IODINE TEST FOR STARCH. 

Material. — Cornstarch. Test tubes. Iodine solution. (See p. 145.) 
Bunsen burner or alcohol lamp. Potato. Medicine dropper. 

i. Put an eighth of an inch of dry powdered starch into a test 
tube. Add water till the tube is two thirds full and shake 
thoroughly. Boil the starch, noting any changes that take place. 

2. Pour a quarter of an inch of the starch paste, as prepared 
above, into a test tube. Half fill it with water and shake 
thoroughly. Add a few drops of the iodine solution. A beautiful 
blue color is the characteristic test of starch. Place the thumb 
over the mouth of the tube and shake gently to mix the color 
evenly. 

3. Shake up a little raw starch in water and test with the 
iodine. How does this compare with the experiment with the 
boiled starch? 

4. Scrape a fresh cut of raw potato. Shake up some of this 
pulp in water and test with iodine. Is starch present? Boil 
some of the pulp and test. 

5. Apply the starch test to various other foods, such as bread, 
crackers, oatmeal, tapioca, beans, rice, etc. 

MICROSCOPIC APPEARANCE OF STARCH. 

Material. — Potato. Microscope. Slide and cover slip. Iodine. Blotting 
paper. 

1. Scrape a fresh cut of raw potato and mount a tiny bit of the 
fine pulp in a drop of water on a slide. Cover with a cover slip. 
Examine with a high power. Make a drawing showing a few of 
the starch grains. Note their fine concentric markings. 

2. Place a drop of iodine on the slide, close to the cover slip. 
Touch a piece of blotting paper to the slide at the opposite edge 



74 PHYSIOLOGY. 

of the cover slip. This should draw the iodine more rapidly under 
the cover slip. Meanwhile, closely watch the starch grains. What 
change occurs? 

3. In the same way examine and test starch grains from beans 
and other seeds ; from apples and other fruits ; from the pith of 
growing corn stalks, etc. 

INSOLUBILITY OF STARCH. 
Material. — Cornstarch. Test tubes. Test-tube rack. 

1. Put a quarter of an inch of cornstarch into a test tube. 
Half fill it with water and shake thoroughly. Note the color. 
Set the tube in the rack and look every few minutes for half an 
hour. If the starch settles and the water becomes clear, shake 
again. Does the starch dissolve in the water? 

INDIFFUSIBILITY OF STARCH. 

Material. — Cornstarch. Glass tube an inch in diameter or small lamp 
chimney. Parchment, at least two inches square. Wet the parchment and 
tie it tightly over the end of the tube. 

i. Shake up starch in water. Pour it into the tube and set it 
in a tumbler. Test what comes through the parchment. Does 
starch pass through? 

2. Make a thin starch paste by boiling starch as before. Pour 
some of the thin paste into the parchment tube. Test what 
comes out. Do you find starch? 

B. SUGARS. 

Material. — Fehling's solution. (See p. 145.) Six raisins. Mortar and 
pestle. Test tubes. Test-tube rack. Cane sugar, beet sugar, maple sugar, 
milk sugar. Corn sirup, maple sirup, molasses, sorghum, honey, candies, 
figs, dates, fresh fruits, dried fruits, jam, jellies. 

1. Half fill a test tube with Fehling's solution and boil to see 
if it is in good condition. No yellow color should appear. If it 
seems all right, keep it for experiment 3. 



FOODS. 75 

2. Crush a few raisins in the mortar. Pour a third of a 
tumbler of water over them and let it stand half an hour or 
so. Taste the liquid. Is grape sugar soluble? 

3. Add about an inch of the grape-sugar solution, obtained 
in experiment 2, to the Fehling's solution, left from experiment 1. 
Shake and boil the mixture. An orange, or yellow, color is the 
characteristic test for grape sugar. Set the tube in the rack. 
Does the color remain uniform throughout the tube ? A sediment 
from such experiments is called a precipitate. 

4. In the same way test cane sugar, beet sugar, maple sugar, 
milk sugar, maple sirup, corn sirup, molasses, sorghum, honey, 
various candies, figs, dates, prunes, fresh and dried fruits, etc. 
Which of these contain grape sugar? Has any kind of sugar 
been added to any of these substances in their preparation for 
market? Is there anything else in them that was not produced 
in the growth of the fruit named in the label? 

DIFFUSIBILITY OF GRAPE SUGAR. 
Material. — Grape-sugar solution. Parchment tube. 

1. Pour grape-sugar solution into a parchment tube. Set this 
in a tumbler. Taste the liquid that filters through the parch- 
ment. Test it with Fehling's solution. 

STUDY OF WHEAT FLOUR. 

Material. — Wheat flour. Muslin bag, three inches wide, four inches 
deep. Strong nitric acid. Strong ammonia. Test tubes. Fehling's solution. 
Quart bowl. 

i. Mix flour and water to form a stiff dough. Put a piece of 
dough, of the size of a hen's egg, into the muslin bag. Tie the 
bag and thoroughly knead it in a bowl of water. Test, with iodine, 
the white sediment in the bowl. 

2. After kneading for half an hour, examine what remains in 
the bag. It is chiefly gluten, one of the forms of proteid. What 
are its physical properties? 



76 PHYSIOLOGY. 

3. Taste the gluten. Does it seem to contain sugar? Test 
the gluten, the water, and the white sediment with the grape- 
sugar test. Do any of them contain grape sugar? 

4. Test the gluten with the proteid test : take a small part of 
it and pour on it a few drops of strong nitric acid. Rinse and 
add a few drops of strong ammonia. Does it show the proteid 
reaction? 

5. Burn some flour on a shovel in the fire. Is there some ash 
left ? This is mineral matter. 

FURTHER STUDY OF MILK. 

Material. — Quart of milk. Lactometer. Graduate (tall glass jar, used 
in chemical laboratory). Basin. Litmus paper. 

1. Pour about a pint of rich milk into a graduate. With a 
lactometer find its specific gravity. 

2. Carefully measure a pint of water and weigh it. Do the 
same with a pint of rich milk. Which weighs more ? 

3. Test skimmed milk with the lactometer. How does it com- 
pare with whole milk? 

4. To a pint of whole milk add half a pint of water. Test with 
the lactometer. 

5. What frauds are sometimes practiced by milk dealers ? Is 
the milk changed by adding something to it, or by taking some- 
thing from it, or by both? What may be added? What taken 
out? What are the best ways to detect such frauds? 

6. If a Babcock milk tester is available, test various samples of 
milk with it to see how much cream they contain. 

7. What is formaldehyde? How is it used in connection with 
milk, and for what purpose ? 

8. Test fresh milk with litmus paper. Is it acid, alkaline, or 
neutral ? 

9. Set the milk in a warm place till it is sour. Test with litmus 
paper. What result? What is the relation between the souring 
and the curdling of milk? 



FOODS. 77 

THE COOKING OF MEAT. 

Material. — Two pounds of round steak. Beaker. Small frying pan. 
Lard. Bowl. Medicine dropper. Caustic soda. Copper sulphate. Stove 
or Bunsen burner. Two-quart pail or kettle. Salt. String. Fork. Funnel 
and filter paper. 

i. Mince half a pound of steak by putting it through a meat 
grinder. Place it in an earthen bowl, pour water over it, and let 
it stand from one to two hours. 

2. Filter the water from experiment i, and test for proteid as 
follows : To half a test tubeful of the liquid add an inch of strong 
caustic soda. Now add one or two drops of a dilute solution 
of copper sulphate. A violet color indicates the presence of 
proteid. 

3. Does water extract some of the nourishing material from 
meat? Is it best to soak meat in water before cooking it? 

4. Put half a pound of lean meat into a quart of water. Slowly 
bring the water to the boiling point and continue boiling for 
twenty minutes. What is the condition of the meat? Test the 
water as in experiment No. 2. 

5. Repeat experiment No. 4, with the addition of three table- 
spoonfuls of salt at the beginning of the experiment. What dif- 
ference results from the addition of salt? 

6. Boil a quart of water in a two-quart pail or kettle. Tie a 
string to a piece of lean meat and let it down into the boiling water. 
Quickly pull the meat out again. What change has taken place? 
Cut into the meat and compare the inside and the outside. 

7. Set a frying pan on the stove or over the burner. When it 
is hot, drop a small piece of steak on it. Quickly turn it over 
and note the effect. What change has taken place ? 

8. Try placing a piece of steak in a cold frying pan and heating 
gradually. 

9. Melt four tablespoonfuls of lard in a frying pan. Continue 
heating till the fat nearly boils. Lay a piece of steak in this hot 
fat. Quickly turn it and observe the effect. 



78 PHYSIOLOGY. 

10. In a cold frying pan, place a piece of steak and some lard. 
Heat gradually. What difference in the cooking of the meat as 
compared with the last experiment? 

FRYING POTATOES. 

Material. — Four potatoes. Teacupful of lard. Frying pan. Stove or 
Bunsen burner. 

i . Melt four heaping tablespoonfuls of lard in a frying pan. 
Pare and slice four potatoes. When the fat is almost boiling put 
half the sliced potato into it. Cook fifteen minutes, turning the 
potato occasionally. Fish out the potato with a strainer. 

2. Repeat the experiment, but put the potato in as soon as the 
lard is melted. What difference in the result? 



CHAPTER XL 
THE DIGESTIVE SYSTEM. 

THE DIGESTIVE ORGANS OF THE RABBIT. 

Material. — Rabbits. (Directions for killing are given on p. 41.) Dis- 
secting boards and paper. Four-penny nails, four for each rabbit. Hammer. 

1. Lay the rabbit on its back, stretch out the front and hind 
feet and tack them down. Slit the skin in the middle line from 
the anterior end of the breastbone to the pelvis, and strip it well 
back to the sides. Observe the thin abdominal muscles, which 
form the ventral wall of the abdomen. Carefully slit this in the 
middle line from the pelvis to the breastbone. From the anterior 
end of this slit cut outward and forward on each side of the breast- 
bone, cutting through the cartilaginous part of the ribs, close to 
the bony part of the ribs. Cut across the anterior end of the 
breastbone and remove it. 

2. Observe the diaphragm, a thin partition separating the chest 
cavity from the abdominal cavity. 

3. Cut outward through the middle of the abdominal wall on 
each side. Turn the flaps far out and tack them down. The lin- 
ing of the abdomen is the peritoneum. Draw the fingers over it to 
learn its smoothness. 

4. Observe the coiled intestine, apparently occupying most of 
the space in the abdomen. In a recently killed animal the intes- 
tines usually show a slow motion, like a mass of worms crawling 
over each other. This is the peristaltic motion, due to the shorten- 
ing and relaxation of the muscles in the walls of the intestines. It 
is a wavelike motion, proceeding from the anterior end to the 
posterior end. 

79 



80 PHYSIOLOGY. 

5. In the anterior part of the abdomen is the dark-colored 
liver overlapping the stomach. In the posterior part of the abdo- 
men the bladder is usually to be seen, varying greatly in size and 
appearance according to the degree of its distention. 

Caution. — Handle the liver very carefully, as it is very delicate 
and may easily be torn. It is full of blood and bleeds readily. It 
should be handled with the fingers. Even the handle of a scalpel 
may tear it, or the finger nails, if it is roughly handled. Compara- 
tively slight bleeding may obscure some important organ. Hence 
it is well to be careful. 

6. Pull the intestine backward and make out the shape, size, color, 
and position of the stomach. Observe how the stomach and liver 
fit together. Push the liver forward. Turn the stomach backward 
and find entering its anterior surface a white tube, the gullet, or 
esophagus. Trace the gullet through the chest. At the larger end 
of the stomach (to the left) is a deep-red body, the spleen. 

7. Find now the connection between the stomach and the 
intestine. Make a drawing of the stomach, showing its shape and 
its connections with the gullet and with the intestine. 

8. Trace the intestine. That part which forms a long loop 
near the stomach is the duodenum. Within this loop is an irregu- 
lar, pinkish, or fatty-looking mass, the pancreas. The pancreatic 
duct is hard to find in the rabbit, much easier in a cat or dog. 
It is a fine, pale tube, entering the intestine. 

9. Observe that the intestine is held in place by a thin, trans- 
parent membrane, the mesentery. Find where the mesentery is 
attached to the abdominal wall. Note the blood tubes radiating 
through the mesentery. In tracing the mesentery, the intestine 
may be dragged out of the abdominal cavity, but care should be 
taken not to tear the mesentery. 

10. Trace the small intestine backward, passing it along with 
the hands. Note that the small intestine runs into the large intes- 
tine at a right angle. The blind end of the large intestine back of 
the entrance of the small intestine is the cecum. In the rabbit it 
is long. In the cat and dog it is short. 



THE DIGESTIVE SYSTEM. 81 

1 1 . Turn the liver forward and find on its posterior surface the 
dark bile sac. The bile duct is a tube which conveys the bile into 
the duodenum. It may often be traced by pressing on the bile sac 
and forcing some of the bile along into the duodenum. It may 
also be traced by cutting into it with fine scissors, and inserting a 
bristle tipped with sealing wax. 

12. Pull the liver back and examine more closely the diaphragm, 
which extends completely across the body cavity, separating the 
chest cavity from the abdominal cavity. The diaphragm is a 
muscle, and its thin, nearly transparent, central part is called the 
central tendon of the diaphragm. 

13. Note the passage of the gullet, aorta, and postcaval vein 
through the diaphragm. 

14. Attached to the dorsal wall of the abdomen are the dark- 
colored, bean-shaped kidneys. 

15. Tie the gullet in two places an inch apart and sever it be- 
tween them. Do the same with the hinder part of the large intes- 
tine, the rectum. Remove the gullet, stomach, and intestines, 
carefully cutting the mesentery along its whole attachment to the 
intestine. Uncoil the whole length of the intestine. How many 
times is the length of the body, including the head, contained in 
the length of the intestine? Compare the lengths of the small 
intestine, cecum, and large intestine. 

16. Cut out about an inch of the small intestine in the middle of 
its course, turn it inside out, wash it thoroughly, and put it into a 
shallow dish of water. The thick mat of short, threadlike projec- 
tions are the villuses (singular villus) . 

17. In the same way examine a piece of the large intestine. 
Are villuses present ? These points may be studied in a piece of 
calf's intestines obtained from the butcher. In examining the 
villuses be careful to keep the piece of intestine under water. 



82 PHYSIOLOGY. 

MODEL OF THE INTESTINE AND MESENTERY. 

Material. — Large rubber tube, eight inches long, an inch or more thick 
(garden hose is good). White court plaster, twelve inches by six inches. 
Red, white, and blue cord, six inches of each. 

i. Rest the arm in a sling made by a handkerchief suspended 
from the shoulder. Press the two thicknesses of cloth together 
just above the arm, to represent the two layers of the mes- 
entery. 

2. Lay the piece of rubber tube across the middle of the court 
plaster. Mark a line along the tube. Fray out the ends of the 
red, white, and blue cords. Attach the frayed ends of the cords 
along the line marked, with the frayed strands passing some on 
one side and some on the other. Now gum the court plaster to 
the tube, so that the cords are between the two layers of court 
plaster after they have covered the tube and extend outward along 
the line on the tube. The tube represents the intestine. The 
court plaster corresponds to the mesentery. The red cords rep- 
resent the arteries, the blue the veins, and the white the lacteals. 

STUDY OF ONE'S OWN MOUTH. 

Apparatus. — Hand mirror. 

i. Close the mouth and shut the teeth together. Is there va- 
cant space between the tongue and the roof of the mouth? Is 
there any unoccupied space in the' mouth ? 

2. Without separating the teeth, try to depress the tongue and 
the floor of the mouth. Can you make space in the closed mouth ? 
Now separate the teeth, still keeping the lips closed. How much 
space can you get? 

3. Keep the teeth closed and run the tip of the tongue over all 
the inside of the mouth that it can touch, noting closely all the 
resulting sensations. 

4. Separate the teeth and run the tip of the tongue all around 
between the cheek and the gums, both above and below. 



THE TEETH. 83 

5." Run the tip of the forefinger all around between the gums 
and the cheeks above and below. 

6. Again place the finger between the gum and the cheek, with 
the thumb on the gum inside the teeth. In this way slip the 
thumb and finger all around both upper and lower gums, noting 
with care the shape and surface at every point. 

7. Run the tip of the finger along the roof of the mouth. The 
front part is the hard palate. The yielding part, farther back, is 
the soft palate. 

8. Face the window and use the hand mirror to examine the 
mouth. The soft palate hangs like a curtain over the back part of 
the tongue, separating the mouth cavity from the pharynx. 

9. From the center of the soft palate hangs the soft, finger- 
shaped uvula. 

10. Perform various acts of breathing to discover the movements 
of the soft palate. 

11. Note the shape of the tongue when it is at rest. Study 
its range of movement. Compare its upper and lower sur- 
faces. 

12. The lining of the mouth is mucous membrane. What is its 
appearance? What seem to be its chief characteristics? How 
does it compare with the skin in color, hardness, moisture, etc. ? 
Can you tell exactly where the skin ends and the mucous membrane 
begins at the edge of the lip ? 

THE TEETH. 

EXTERNAL FEATURES OF A TOOTH. 

Material. — Well-cleaned incisors, one for each student. 

1. Examine an incisor. It has the following parts : (a) the 
crown, the part that is above the gum ; (p) the root, the part 
buried beneath the gum ; (c) the neck, a more or less constricted 
part dividing the crown from the root, at about the surface of the 
gum ; (d) the hole, at the tip of the root. 



84 PHYSIOLOGY. 

STRUCTURE OF A TOOTH. 

Material. — A tooth and a large spool, cork, or small block for each 
student. Sealing wax. Alcohol lamp or Bunsen burner. Grindstone. 

Prepare a longitudinal section of a tooth as follows : Embed a 
tooth, lying on its side, in sealing wax on the end of a spool, cork, 
or block of wood. With a grindstone grind away one half, show- 
ing the pulp cavity to the tip of the root, as shown in Fig. 55, 
Part I. The following parts should be clearly distinguished : — 

1. The pulp cavity, communicating with a hole in the tip of the 
root, through which the nerve and blood tube entered. 

2. The bulk of the tooth is made up of a substance called 
dentin (ivory). 

3. The crown of the tooth has a covering of very hard sub- 
stance, enamel. 

4. The root is covered by a bony substance called cement. 
Make a drawing of the surface thus exposed, naming the parts. 

EFFECT OF ACID ON TEETH. 
Material. — A tooth. Acetic acid or vinegar. 

1. Place a drop of strong acetic acid on a clean tooth. How is 
the tooth affected? 

2. Cover a tooth with acetic acid. Watch for several days. 
What is the result? . 

3. Are your own teeth ever affected by vinegar, tart apples, sour 
grapes, lemon juice, pickles, etc? How do you explain such 
effects? What application can you make of such experiences in 
the better care of your teeth ? 

THE KINDS OF TEETH. 

Material. — A set of four teeth, one of each kind, for each four students. 
Skull or lower jaw, showing the holes in the jaws where the roots of the teeth 
fitted. 

1. The crown of the incisor is chisel-shaped. But the root is 
flattened in the opposite direction, i.e. at right angles to the jaw, 



THE TEETH. 85 

instead of parallel with it as is the case with the crown. Examine 
a skull or jawbone from which teeth have been extracted, in order 
to see the cavities into which the roots fitted. 

2. The canine tooth has a conical crown and a longer root than 
the incisor. 

3. The bicuspid, or premolar, has two points on the top of the 
crown. What kind of a root has the bicuspid ? 

4. The molar has a cuboidal crown and, usually, two or three 
roots. 

5. Make two drawings of each of these four kinds of teeth, a 
front view (outer surface) and a side view (surface next to another 
tooth). 

THE ARRANGEMENT OF THE TEETH. 

Material. — Hand mirror. Skull with full set of teeth or model of a 
half jaw with full set of teeth. 

1. Beginning at the middle of the front of the mouth, there 
are (in the normal adult) eight teeth in each half jaw : two incisors, 
one canine, two bicuspids, and three molars. 

2. Examine your own teeth by means of the mirror. If the 
complete set is not present, which ones are lacking? How do you 
account for their absence? 

3. Shut the teeth together. Do the upper and lower front 
teeth meet squarely ? If not, which overlap ? 

4. Are the upper and lower front teeth of the same size ? Com- 
pare the upper and lower molars. Which are larger ? Can you 
account for this? 

DISSECTION OF THE HEAD OF THE RABBIT. 

Material. — Rabbits. Dissecting set. Dissecting boards. Heavy paper. 

1. Remove the skin from the head. Observe the cartilages of 
the ears and cut them off close to the head. 

2. Below and back of the ear is an irregular pinkish mass, the 
parotid salivary gland. The duct which conveys the saliva runs 
forward over the cheek and opens on the inside of the cheek. It 



86 PHYSIOLOGY. 

is usually hard to see, as it is thin-walled, slender, and of about 
the same color as the sheaths of the muscles on which it lies. It 
may easily be mistaken for a nerve, several of which should now be 
in sight. This duct is much more readily traced in a dog. With 
sharp, fine-pointed scissors cut into the edge of the duct, insert a 
black bristle and push it toward the front. 

3. Just back of the angle of the lower jaw find a roundish body, 
the submaxillary salivary gland. Its duct runs forward inside of 
the lower jaw and opens under the front part of the tongue. Trace 
as directed above. It is rather difficult to trace in the rabbit, but 
comparatively easy in the dog. 

4. The infra-orbital gland is just below the front of the eye, and 
its duct opens near that of the parotid gland. 

5. The sublingual salivary gland is a small, slender gland close 
to the inside of the lower jaw, in front of the base of the tongue, 
and its duct opens near that of the submaxillary. 

6. Observe the muscle that covers the outside of the back part 
of each lower jaw. This is the masseter muscle. Place the fingers 
on the angles of your own jaw and note the action of the masseter 
muscles in shutting the teeth firmly together. In the rabbit note 
the attachment of the masseter muscle to the under edge of the 
cheek bone. Trim the muscle entirely away, noting carefully all 
its connections. 

7. The temporal muscle is attached to the thin wing, or process, 
of the lower jaw in front of the hinge and passes up, inside the 
arch of the cheek bone, and spreads over the temple. The short- 
ening of the masseter and temporal muscles is what shuts the jaws 
together. Remove the temporal muscle, observing closely all its 
relations. Place the tips of the fingers on your temples and shut 
the teeth firmly together. The hardening of the temporal muscles 
is felt. 

8. After removing the submaxillary glands a muscle may be 
found, on each side, attached to the inside of each half jaw near 
their union in front. These are the digastric muscles. When they 
shorten they pull down the lower jaw. Trace these muscles to 



HEAD OF RABBIT. 87 

their attachments at both ends. Review these points till you 
understand how the jaw is opened and shut. 

9. Cut away the soft membrane on the side of the mouth. 
Note its inner surface. Split the two halves of the lower jaw apart 
in front with a strong knife, used from below. Entirely remove 
one half jaw, noting a muscle attached to the inner surface of the 
back part of the jaw. Look at the inner surface of the jaw for 
the hole where the nerve and blood tube entered it. Do you find 
a hole on the outside of the jaw? 

10. Examine the tongue. How much space does it fill when 
the mouth is closed? What is its shape? Can you distinguish 
on its surface the projections called papillas ? 

11. Examine the roof of the mouth. Press against it to find 
whether or not there is bone back of the soft membrane. This 
is the hard palate. * Note any markings or peculiarities of appear- 
ance. Follow it back till you reach the soft palate, which has no 
bony wall supporting it. Follow the soft palate back, cutting 
away so much as is necessary of the lateral wall, making the cut 
along the level where the teeth meet. 

12. Back of the soft palate is the cavity called the pharynx, a 
direct continuation of the mouth. Trace forward the passage from 
the pharynx, over the soft palate, into the nasal passages, above 
the hard palate. Trace the pharynx downward and backward to 
two passageways : the nearer opening is the glottis, or opening to 
the windpipe, leading to the lungs; the farther opening is the 
beginning of the gullet, or esophagus, leading to the stomach. 

13. Between the glottis and the base of the tongue find the 
epiglottis, a spoon-shaped cartilage, which most of the time stands 
up, close to the base of the tongue, but when food passes, it turns 
back and down and covers the glottis, so that food does not enter 
the windpipe. Press the epiglottis down ; now release it. Study 
these parts till their actions are clear to you. 

14. Split the soft palate and turn the parts aside to find on the 
sides of the pharynx the small openings of the eustachian tubes 
that lead outward on each side to the cavity of the middle ear. 



PHYSIOLOGY. 



Upper 



Left Upper /*"} 

rY 



o 



- n , 



» \ Right Upper 



CO 



n 



Left 



Right 





1 i 



V / 








/ ~l 

P 


Left Lower 


s % 






',, / Right Lower 






"^ 


e: 


rDd 










Lower 




Incisor 




v -J 






Extracted •%? 


Canine 




C> 






Not appeared ( 


Bicuspid 


1 


CD 






Fillings — Red. 


Molar 




Q 






Cavities — Blue. 


Plot < 


df Teeth of 






Age 



Fig. 4. Tooth Blank. 



TOOTH BLANK. 89 

DIRECTIONS FOR FILLING OUT THE TOOTH BLANK. 

1. Be careful to indicate the right jaw teeth on the right-hand 
side of the blank and not reversed as shown in the mirror. Sup- 

.pose the sheet were waxed and then doubled crosswise along the 
line between the upper and lower jaws. Then if you were to insert 
the fold far back into the mouth and shut the teeth on it, you 
would make imprints there as in the blank. 

2. Begin at the middle of the upper jaw. If you have the first 
incisor, trace over the dotted line representing this tooth in the 
blank, making the dotted line continuous. Proceed back in the 
same way. 

3. If a tooth has never appeared in any of the regular places, 
simply leave the dotted line as it is. 

4. If a tooth has been extracted, leave the dotted line un- 
changed, but mark a star in the center. 

5. Indicate with blue ink all unfilled cavities. Show as clearly 
as you can the position and size of the cavities. 

6. In the same way indicate by red ink all fillings. A gold 
crown, or porcelain crown, may be indicated by an encircling red 
line. 

7. If teeth are present in unusual positions, indicate them by 
inserted outlines. 

8. If there is good evidence that a new tooth is about to appear, 
indicate the fact in the blank. 

9. Additional facts may be written on the back of the sheet, if 
they cannot be well shown on the plot. 

10. Sum up the number of teeth in each half jaw, number of 
upper, lower, right and left, and place the figures under the words 
printed around the margin of the plot. Place the total number in 
the center of the plot. 

11. If it is possible, secure the assistance of your dentist, or 
physician, in filling out this blank. 

12. Write your name in full. State your age in years at your 
last birthday. 



90 PHYSIOLOGY. 

THE MOVEMENTS OF THE JAW. 

Material. — Human skull. Model of the head. 

i. Observe how the lower jaw is joined to the skull. What 
kind of a joint is it ? Compare the skull with the dissection of the 
rabbit's head, and with your observations of your own temporal 
and masseter muscles. Compare also with a model of the human 
head. Can you see how the temporal and masseter muscles were 
situated? How they were connected? How they work? 

2. Place the tips of the fingers just below the cheek bones. 
Open the mouth wide. Can you feel a bone projecting beneath 
the cheek bone ? Can you find, by looking at the cleaned jaw- 
bone, what part it is that projects? 

3. Open and shut the teeth as in biting. Move the jaw from 
side to side. Glide the lower jaw forward and backward. Study 
all the movements of which the jaw is capable. 

4. Look on the inside of the jawbone for a hole through which 
the nerve and blood tubes entered to supply the bone and the 
teeth. 

WHERE THE SALIVA ENTERS THE MOUTH. 
Material. — Hand mirror. Small spoon. 

1. Pull out and back the corner of the mouth. On the inside 
of the cheek, opposite the second molar, look for a small red spot. 
It looks like the wound made by a bee sting, or like a hole made 
by a thorn. It is the opening of the duct from the parotid sali- 
vary gland. Find the corresponding opening on the other side. 
Wipe away any moisture around this opening and watch to see if 
saliva issues from it. 

2. Turn the tongue up and back. On the floor of the mouth 
observe two conical elevations. At their tips are the openings of 
the ducts from the submaxillary salivary glands. Can you prove 
that liquid issues from them? Try holding a tiny spoon under the 
tips of the projections. 



SWALLOWING. 91 

THE PROCESS OF SWALLOWING. 

Material. — Soft rubber tube, two feet long, one inch in diameter. Piece 
of soap. Darning ball. Child's stocking. 

i. Perform the act of swallowing. Stop in the middle of the 
act. Note the choking sensation. 

2. Place the finger on the Adam's apple and perform the act 
of swallowing. What motion do you feel ? The larynx is pulled 
upward and, at the same time, the epiglottis covers the glottis • 
hence the choking sensation, if the parts are held in this position. 

3. Push an egg-shaped piece of wet soap into a rubber tube. 
Push it along by repeatedly closing the hand behind it. Let three 
or four persons lightly hold the rubber tube, with their hands in 
contact. By shutting the hands in succession the piece of soap 
may be pushed along the tube. This shows how the successive 
shortening of the circular muscle fibers of the gullet pushes the 
food along to the stomach. 

4. Instead of rubber tube and soap, a darning ball and child's 
stocking may be used. 



CHAPTER XII. 
ACTION OF THE DIGESTIVE LIQUIDS. ABSORPTION. 

DIGESTIVE ACTION OF SALIVA. 

Material. — Saliva. Starch paste. Test tubes. Iodine solution. Fehl- 
ing's solution. Alcohol lamp or Bunsen burner. Water bath. Thermometer. 
Litmus paper, red and blue. Small rubber band. 

i. Chew paraffin, or rubber, and collect about two inches of 
saliva in a test tube. Test it with litmus paper. Is it acid, alka- 
line, or neutral ? 

2. Pour half of the saliva into another test tube and dilute it with 
four times as much water. Set the tube in the water bath at about 
40 C. (99 F.). After fifteen or twenty minutes test by adding 
Fehling's solution and boiling. , Does it contain grape sugar? (See 
experiment 3, p. 75.) 

3. Make a thin starch paste and test with Fehling's solution, as 
in experiment 2. 

4. Pour about an inch of dilute saliva into a test tube. Add 
twice as much starch paste. Shake gently to mix thoroughly. 
Place in the water bath, at about 40 C. Once every five minutes 
pour a little of the mixture into two test tubes. Test one for starch 
(iodine test) ; test the other for grape sugar (Fehling's solution). 
Is any change taking place ? 

5. Boil some diluted saliva in a test tube. Mix this with starch 
paste and keep in the conditions given in experiment 4. Test with 
Fehling's solution. 

6. Mix starch paste and saliva as in experiment 4, but set the test 
tube in ice water. After twenty minutes test one half of it with 
Fehling's solution. Place the other half in the warm water for 
twenty minutes. Test for grape sugar. What results? 

92 



ACTION OF GASTRIC JUICE. 93 

DIGESTIVE ACTION OF GASTRIC JUICE. 

Material. — Hard boiled white of egg. Pepsin. Hydrochloric acid. 
Water bath. Thermometer. Fine wire sieve or wire screen. Test tubes. 

Preparation. — Make an artificial gastric juice by mixing 
together ioo c.c. of water, 4 c.c. of strong hydrochloric acid, 
and 1 gram of pepsin. Mince half of the hard-boiled white of 
egg by rubbing it through the sieve. 

1. Place about one fourth of an inch of the minced white of 
egg in a test tube. Half fill with the gastric juice. Keep in a water 
bath at about 40 C. (99 F.). Do not shake the tube. Label " 1 
(minced egg + pepsin + acid + heat + quiet)." Watch during the 
remainder of the day and again the next day. 

2. Repeat experiment 1, but shake the test tube frequently. 
Label " 2 (minced egg + pepsin -f acid + heat + shaking)." Observe 
as before. 

3. Repeat experiment 2, but use a few large lumps of egg. Label 
"3 (lump egg + pepsin + acid + heat -f shaking)." Watch closely. 

4. Repeat experiment 2, but omit the pepsin. Label " 4 (minced 
egg -f acid + heat + shaking) ." 

5. Repeat experiment 2, but omit the hydrochloric acid. Label 
"5 (minced egg+pepsin+ heat + shaking)." 

6. Repeat experiment 2, but set the tube in ice water. Label 
" 6 (minced egg + pepsin + acid + cold + shaking)." Is the egg 
digested ? On the second day transfer the tube to the warm bath. 
Does digestion now take place ? 

7. Repeat experiment 2, but use pepsin that has been boiled. 
Label " 7 (minced egg + acid + boiled pepsin + heat -f shaking)." 
Carefully describe and compare the results of all these experiments. 
Which of the conditions is most like that of the normal stomach ? 

ACTION OF GASTRIC JUICE ON MILK. 

Material. — Milk. Pepsin. Rennet, or rennin. Water bath. Test tubes. 

1. Add a few drops of rennet, or rennin, to half a test tubeful 
of milk. What change takes place? 



94 PHYSIOLOGY. 

2. Add gastric juice and set in the warm bath. Shake frequently. 
Note the changes for several hours. 

DIGESTIVE ACTION OF PANCREATIC JUICE. 

Material. — Pancreatin. Cooking soda. Butter. Water bath. Ther- 
mometer. Test tubes. 

i. Artificial pancreatic juice. Prepare this by adding 5 grains 
of pancreatin and 15 grains of cooking soda to 100 c.c. of water. 

2. Pancreatic digestion of starch. Add a little dilute starch 
paste to half a test tubeful of artificial pancreatic juice. Keep in 
the warm bath at 40 C. Test with Fehling's solution. What does 
this show? 

3. Pancreatic digestion of fat. Shake up a little melted butter 
with half a test tubeful of artificial pancreatic juice. Does it form 
a good emulsion? 

4. Pancreatic digestion of proteid. Add a little minced hard 
boiled white of egg to half a test tubeful of artificial pancreatic 
juice. Keep in the warm bath. Shake frequently. Is the egg 
digested ? Compare with the pepsin digestion of proteid (experi- 
ment 2, p. 93). What differences in the chemical condition are 
required by pepsin and pancreatin? 

THE DIGESTIVE ACTION OF BILE. 

Material. — Bile. Butter or olive oil. Test tubes. Litmus paper. 

i. Test bile with litmus paper. Is it acid, alkaline, or neutral? 
2. Shake up a little olive oil or melted butter with bile. Does 
it form an emulsion? 

TESTS OF PEPTONE. 

Material. — Commercial peptone. Fehling's solution. Parchment tubes. 
(See p. 74.) Tumblers. Minced boiled white of egg. 

1. To a solution of pure peptone add a few drops of Fehling's 
solution. The characteristic test of peptone, on adding Fehling's 



ABSORPTION. 95 

solution, is a rose color. Adding a little more of the solution 
should change it to violet. 

2. Pour commercial peptone solution into a parchment tube. 
Set the tube in a tumbler. Does the peptone pass through the 
membrane? 

3. Digest minced white of egg as in experiment 2, p. 93. 
Pour the resulting liquid into a parchment tube. Does it pass 
freely through the membrane? Compare with experiment 4, 
p. 94. 

4. Test with Fehling's solution the liquid that passes through 
the membrane in experiment 3. Compare with experiment 1. 

ABSORPTION. 

GROSS STRUCTURE OF THE SMALL INTESTINE. 

Material. — Piece of small intestine of calf, a foot long. Have the 
butcher rinse this out by running a stream of water through it. Sauce 
dishes, one for each two students. Dissecting set. Linen tester. 

i. With scissors cut the intestine into half-inch lengths. Turn 
half the pieces inside out, using the forceps. 

2. In each dish place two pieces of intestine, one piece turned 
inside out, the other not. Do not lift the pieces out of the water 
to examine them. 

3. Observe the little threadlike projections on the pieces turned 
inside out. Each projection is a villus. Can you tell by the 
appearance which pieces have been turned inside out? 

4. Split one of the pieces lengthwise and spread it out in the 
water with the inside up. Hold a linen tester down over it. Can 
you count, or make an estimate, of the number of villuses in the 
square shown ? If so, measure this square and calculate the number 
of villuses to a square inch. 

5. Examine the cut end of the section. Can you distinguish 
two coats, the outer muscular coat and the inner mucous coat? 

6. Can you distinguish the line along which the mesentery was 
attached? 



96 PHYSIOLOGY. 

MODEL OF THE SMALL INTESTINE. 
Material. — Rubber coin pad or rubber bath brush. 

i. Roll the pad into a cylinder, with the upper, or rough, sur- 
face, inside. The finger-shaped projections represent the villuses 
and the flat pad corresponds to the body of the mucous mem- 
brane. The villuses are extensions of the mucous membrane. 

2. Slip the tube thus made into the model of the intestine and 
mesentery (see p. 82), and you have a fairly complete model of 
the intestine, — mesentery, arteries, veins, lacteals, muscular coat, 
mucous coat, and villuses. 

MICROSCOPIC STRUCTURE OF THE SMALL INTESTINE. 

Material. — Prepared slides, showing cross sections of the small intestine 
of cat, rabbit, or dog, in which the capillaries are injected. Retort stand with 
clamp. Microscope. 

1. Fasten a slide, showing a cross section of small intestine, by 
one end in the clamp and set the clamp high on the rod, so that 
you can look through the slide toward a window. With the naked 
eye try to distinguish (a) the outer, muscular coat ; (p) the mucous 
coat ; (/) the villuses, extending from the mucous coat toward the 
center. 

2. Examine a slide under a very low power, say a three-inch 
objective, so that the field of view will include all, or nearly all, of 
the section. Observe the same points as in No. 1. Note also the 
red network of capillaries in all parts of the section. Do you 
see any of the larger blood tubes? In which coat? Why not 
elsewhere? 

3. Under a two-thirds inch objective, study the arrangement of 
the capillaries (a) in the muscular coat ; (b) in the mucous coat ; 
(V) in a villus. 

4. Put on a high power. Try to distinguish the epithelial cells, 
which form the outer layer of each villus. 

5. There are lacteals in each villus, but they are invisible. 



ABSORPTION. 97 

EFFECT OF BILE ON ABSORPTION. 

Material. — Ox bile. Two large beakers. Filter paper. Olive oil. Lit- 
mus paper. 

i. Stretch a sheet of filter paper across the top of a large beaker. 
Moisten the paper with water. Place a teaspoonful of olive oil on 
the paper. 

2. Repeat experiment i, but wet the paper with bile instead of 
water. Compare with experiment i. 

3. Test bile with litmus paper. Is it acid, alkaline, or neutral? 

THE LACTEALS AND MAIN LYMPH DUCT. 

Material. — Kitten or puppy. Chloroform. Dissecting board. Heavy 
paper. Half pint of cream or very rich milk. Clamp (bull-dog forceps). 
Dissecting set. 

i. Feed the kitten or puppy with cream or very rich milk. 
Two or three hours later kill it as directed on p. 41. After it has 
been quiet five minutes, open the chest and abdomen. Pull aside 
the heart and left lung. Close to the aorta there should be found 
a tube filled with a white liquid. This tube is the main lymph 
duct, or thoracic duct. 

2. Find where the main lymph duct (thoracic duct) empties 
into the left subclavian vein, close to its junction with the jugular 
vein. Clamp the duct at this point to prevent the escape of the 
chyle into the vein. 

3. Trace the lymph duct back along the spinal column, till it 
disappears where it came through the diaphragm. Find it again 
in the dorsal part of the abdomen, just posterior to the diaphragm. 
Its enlargement is the receptacle of the chyle. 

4. Spread out the small intestine. Running through the mes- 
entery there should be seen fine radiating tubes, filled with a white 
liquid. Prove that it is a liquid, by pressing on the tubes and push- 
ing the liquid along. These tubes are the lacteals, and the liquid 
is the chyle. Can you trace them back to the walls of the intestine ? 
Note how they converge toward the receptacle of the chyle. 



CHAPTER XIII. 
THE BRAIN. 

DISSECTION OF THE BRAIN AND CRANIAL NERVES. 

Material. — Rabbit, cat, or dog. If possible, use a specimen with the arte- 
ries injected. Bone forceps. Support (see p. 15). Dissecting set. Chloro- 
form. Large crock or jar. Small sponge. Small meat saw, for dog or sheep 
skull. Alcohol. Hardening liquid: water 100 c.c; formalin, 4 ex.; potas- 
sium bichromate, 2 g. 

i. Kill the animal as directed on p. 41, remove the internal 
organs, and place on the support (see p. 15). 

2. Remove the skin and muscles from the top and sides of the 
head. Cut through the ear cartilages close to the skull. 

3. With the bone forceps cut through the bone between the 
eyes. Carefully cut inward and backward till the brain is reached. 
Break away the bone by inserting one blade of the forceps 
under the bone and prying upward and outward. 

4. Uncover the whole of the brain. If this work has been 
carefully done, the brain will still be covered by a tough membrane, 
the dura mater. 

5. All the anterior part of the brain is the cerebrum. 

6. The lower back part of the brain, separated by a deep groove 
from the cerebrum, is the cerebellum. 

7. Note that the cerebrum is divided into right and left hemi- 
spheres. 

8. The irregular ridges on the surface of the brain are the con- 
volutions. 

9. With the forceps pinch up a fold of the dura mater near the 
middle line and cut through it with the scissors. From this open- 

98 



THE BRAIN. 99 

ing slit the dura mater along the top of the brain, from front 
to back, about half an inch from the middle line on each 
side. 

10. From the middle of each slit cut outward and turn down 
the flaps of dura mater, to expose the brain. Cut across the re- 
maining central strip, pulling it upward as you do so. Remove 
this partition between the hemispheres. 

1 1 . With the dura mater removed, the convolutions should show 
more clearly. 

12. The thin covering still on the brain is the pia mater. 

13. At the posterior end of the brain find the spinal cord, as it 
enters the cavity of the spinal column. 

14. Note the slender extensions at the anterior end of the brain. 
These are the olfactory lobes. 

15. Cut across the olfactory lobes and with the handle of the 
scalpel gently lift the anterior end of the brain. 

16. An inch or so back find two white cords entering the base 
of the brain. These are the optic nerves. Cut off the optic nerves 
close to the bone. After removing the brain, cut away the bone 
and trace one of them to the eye. 

17. Farther back, under about the center of the brain, is a 
smaller pair of nerves, the third pair of cranial nerves. Cut them, 
and all the rest of the nerves, as far from the brain as possible. 

18. The fourth pair extend up on each side into a groove be- 
tween the cerebrum and cerebellum. 

19. Back of these, but nearer the middle line, and considerably 
larger, is the fifth pair of cranial nerves. Each of these has two 
roots, like a spinal nerve. 

20. The sixth pair are slightly farther back, smaller, and close 
to the middle line. 

2 1 . The seventh pair, or facial nerves, are a little back of the 
fifth pair. 

22. Closely behind the seventh pair comes the eighth pair, the 
auditory nerves, each apparently a double nerve. 

23. The ninth, tenth, and eleventh pairs are very close to each 



ioo PHYSIOLOGY. 

other in a row well up on the sides of the spinal bulb, just back of 
the cerebellum. 

24. The ninth pair, or glossopharyngeal nerves, are a little 
back of, but much higher than, the eighth pair. 

25. Closely back of the ninth comes the tenth pair, or vagus 
nerves. 

26. The eleventh pair, the spinal accessory, arise, in part, from 
the spinal cord. 

27. The twelfth pair, or hypoglossal nerves, arise about oppo- 
site the eleventh, but close to the middle line. 

28. Cut off the spinal cord where it passes out of the skull. 
That part of the spinal cord which lies within the skull is called the 
spinal bulb. It is considered a part of the brain. 

29. In a large jar place a layer of cotton batting, two or three 
inches thick. Carefully place the brain on this and cover with an 
ample amount of the hardening liquid. 

30. Let the brain harden in this liquid for a week or two. Then 
transfer it to strong alcohol and keep till needed. 

STUDY OF A HARDENED BRAIN. 

Material. — Brain, hardened as described in the last section. If possible, 
use a brain with the arteries injected. Dissecting set. 

i. Review the external features of the brain, following the 
directions in the preceding section. 

2. Press down the cerebellum to see the deep groove between 
it and the cerebrum. The thin membrane covering the brain and 
dipping down into the grooves is the pia mater. 

3. Press down the spinal bulb and tear away the pia mater 
where it passes from the cerebellum to the spinal bulb. Note, 
between the bulb and the cerebellum, a space covered by a thin 
membrane. Cut through this membrane. The cavity is the 
fourth ventricle of the brain. Observe the two ridges bounding 
the sides of the fourth ventricle. At the point of their conver- 



THE BRAIN. 101 

gence, posteriorly, observe the opening of the central canal of the 
spinal cord. 

4. Examine the under surface of the brain and review the roots 
of the cranial nerves. 

5. With a sharp scalpel or razor cut off a thin slice from 
the end of the spinal bulb. Can you distinguish the white matter 
and the gray matter? 

6. Gently separate the cerebral hemispheres and note the band 
of white fibers connecting them. This band is the corpus callosum. 

7. With a sharp scalpel or razor split the brain vertically and 
longitudinally in the middle line. What cavities do you find? 
Note the branched appearance of the inner surface of the cere- 
bellum. This is the arbor vitae. 



CHAPTER XIV. 
TOUCH, TASTE, SMELL. 

CUTANEOUS SENSATIONS. 

Material. — Model showing the structure of the skin. Microscopic slides 
of cross sections of the skin. Feather. Dividers, with blunt points. Red ink. 
Black ink. Two pens. Hot and cold water. Three basins. Ten-penny nails. 
In the following experiments the person experimented on is to be blindfolded. 

i. Study the model to see the touch corpuscles. Examine the 
sections also to see the touch corpuscles. 

2. With a fine- tipped feather lightly touch the skin at various 
points on the front and back of the hand. Are all parts equally 
sensitive ? Repeat with different parts of the face and neck. In 
the same way test other parts of the body at home. Compare the 
results with the statements made in the physiologies. 

3. Gently touch the skin of the back of the hand with a pen 
dipped in black ink. Let the person experimented on indicate 
the spot by trying to touch the same place with a pen dipped in 
red ink. Repeat in various places on the back of the hand, palm, 
arm, face, etc. Does he locate the spots accurately? Does the 
degree of accuracy vary in different places ? 

4. Shut the dividers till the tips are a quarter of an inch 
apart. Gently touch the palm of the hand. Can you distinctly 
feel the two tips, or do they seem to be only one ? Try various 
parts of the hand, arm, face, tip of the tongue, neck, etc. Set the 
tips at various distances, and repeat. How do these various places 
compare in sensitiveness as shown by distinguishing the two points 
of touch ? Compare your results with the statements made in the 
physiologies. 

192, 



TOUCH, TASTE, SMELL. 103 

5. Set the tips of the dividers half an inch apart and touch the 
inside of the forearm near the elbow. Draw the tips, parallel to 
each other, slowly down the forearm, along the palm and along 
the middle finger to its tip. Do the tips seem equally distant all 
the time? 

6. Draw the separated tips crosswise on the arm. Compare 
with experiment 5. 

7. Touch the skin at various points with the tips of large wire 
nails, hot, warm, and cold. How do different areas compare in 
sensitiveness to heat and cold? 

8. Fill three basins with hot, cold and tepid water, respectively. 
Dip one hand into the hot, the other into the cold, water. Now 
plunge both into the tepid water. Explain the sensations. 

9. Cross the tips of the first and second fingers. Let another 
person apply the tips of these crossed fingers to a marble, to a 
pencil, etc. What sensation do you get ? 

10. Lay the hand on the table, palm upward. Try to guess the 
weights of various objects, placed on the palm by another person. 
Try two equal weights, one spherical, the other pounded out flat. 
How do they compare in apparent pressure? Try equal weights 
of various shapes. Take two silver dollars. Heat one and cool 
the other. Place them in succession on the same area. 

11. Muscular sense. While still blindfolded, extend the fore- 
arm. Let another person place various weights in the hand. 
Estimate their weight by moving the hand up and down. Com- 
pare equal weights of various substances, such as lead and wood, 
stone and bread, ice and hot potato, etc. 

THE SENSES OF TASTE AND SMELL. 

Material. — Salt, sugar, vinegar, quinine. Medicine dropper. Apple, 
onion, potato, cheese. The person experimented on is to be blindfolded. 

i. Wipe the tongue dry, and place on it a few grains of salt. 
Do you taste it immediately? Try sugar, soda, etc. 

2. Prepare a weak solution of salt. With a medicine dropper 
place a drop of it on the tip of the tongue. After a minute place 



104 PHYSIOLOGY. 

a drop on the base of the tongue. Then on the middle and then on 
the sides. Where is the taste for salt most keen? 

3. In the same way test with sugar water, weak vinegar, any 
bitter liquid, etc. 

4. Place on the tongue in succession bits of apple, potato, onion, 
cheese, etc. 

5. Repeat experiment 4, while holding the nostrils closed. Can 
these substances be readily distinguished? 

6. Rinse the mouth with ice water. Now test the sense of taste. 
Is it as acute as before ? Rinse the mouth with water as hot as 
can be borne. How does this affect the ability to taste objects? 

THE PAPILLAS OF THE TONGUE. 

Apparatus. — Hand mirror. Slide with section of the tongue. Microscope. 

1. Observe the fine projections over most of the surface of the 
tongue. These are the filiform papillas. 

2. Scattered among these are small red spots, the fungiform 
papillas. 

3. Near the base of the tongue are about a dozen larger, wart- 
like bodies, arranged in the form of a letter V with its a P ex toward 
the base of the tongue. They are the circumvallate papillas. 

4. Examine a section of the tongue under a high power of the 
microscope to see the taste buds and other nerve endings in the 
papillas. 



CHAPTER XV. 
EXTERNAL FEATURES AND STRUCTURE OF THE EYE. 

EXTERNAL FEATURES OF OUR OWN EYES. 

Apparatus. ■ — Hand mirror. 

i. Compare the upper and lower eyelids. Which covers the 
larger part of the eye ? 

2. Open the eye wider than usual. Which lid moves farther? 

3. Close the eye more than usual. Do the two lids move 
equally ? 

4. Compare the upper and lower eyelashes. 

5. With thumb and finger gently feel of the edge of the upper 
lid from right to left. Close the eye and repeat the experiment 
farther up on the lid. How does the lid vary in thickness ? 

6. The white of the eye is the sclerotic coat. 

7. The circular colored area is the iris. Is its color uni- 
form? 

8. The dark spot in the iris is the pupil. Is it exactly in the 
center of the iris? Is the pupil of the same color in all 
healthy eyes ? What gives it this color ? 

9. Can you be sure that the iris is not at the very front of the 
eye, but is covered by the transparent cornea? Look at the side 
of another person's eye. 

10. Pull down the lower lid. The lining of the eyelid and the 
outer covering of the front of the eyeball is the conjunctiva. Can 
you see the bottom of the cavity made by the fold of the con- 
junctiva when you pull down the lower lid? 

11. Observe the blood tubes in the conjunctiva, both on the 
eyeball and on the inside of the flfcls. 

105 



106 PHYSIOLOGY. 

12. In the inner angle of the eye observe a small pinkish or 
yellowish spongy elevation. This is the caruncle. Pull down the 
lower lid to see it better. 

13. A short distance from the caruncle toward the iris note a 
slight vertical fold. This is the rudiment of a third eyelid. Watch 
this while the head turns to right and left. Look for the third 
eyelid in the cat, dog, horse, cow, and bird. 

14. Pull down the lower lid. On its edge, about a quarter of 
an inch from the inner angle of the eye, find a small hole. This 
is the opening of the duct leading into the nasal cavity. This duct 
carries off the liquid that moistens the conjunctiva. Look for the 
corresponding opening on the edge of the upper lid. 

15. Again pull down the lower lid. Look closely at its edge for 
a row of very small holes. These are the openings of the ducts of 
the oil glands, which oil the eyelashes and the edge of the lid. 

THE MUSCLES OF THE EYEBALL. 

Material. — Head of mammal ; cat, rabbit, dog, calf, or sheep. Bone 
forceps. Meat saw. Dissecting set. Cut away the bone at the outer angle 
of the eye socket. With the skull of calf or sheep, a saw will be needed ; for 
smaller mammals, bone forceps will serve. 

1. With scissors trim away the white membrane (transparent in 
life) around the front of the white of the eye. It is the conjunc- 
tiva, which covers the front of the eyeball, and then turns back to 
line the inside of the eyelids. 

2 . Find a muscle running along the roof of the eye socket, which 
passes through a loop of tendon near the edge of the orbit, and 
turns outward to its attachment to the top of the eyeball. This 
is the superior oblique muscle. 

3. Beneath the eye find a muscle which arises in the inner front 
part of the orbit and turns outward to its attachment to the under 
surface of the eyeball. This is the inferior oblique muscle. 

4. Attached to the top of the eyeball is the superior rectus 
muscle, below is the inferior rectus muscle, at the sides are the 
internal rectus muscle and the external rectus muscle. Find the 



EXTERNAL FEATURES AND STRUCTURE OF EYE. 107 

origin of these four muscles, with that of the superior oblique, at 
the bottom of the eye socket. 

5. Dissect away the fat and other tissue around these muscles, 
and find a cone-shaped muscle attached to the back of the eye- 
ball. 

6. Within this last muscle find the cylindrical optic nerve. 
Does it enter the center of the back part of the eyeball? 

EXTERNAL PARTS OF THE EYEBALL. 

Material. — Eyes of ox, sheep, or hog. 

1. Observe the clear front part of the eye, the cornea. Its 
wider end was at the inner angle of the eyelids. 

2. Around the cornea find a whitish membrane (in life trans- 
parent), the conjunctiva, which a short distance back from the 
cornea separates from the eyeball to turn forward and line the eye- 
lids. 

3. The severed muscles of the eyeball, the fat which forms the 
cushion for the eyeball, and other tissues should be trimmed away, 
leaving the optic nerve. 

4. Place the eyeball in its natural position and make drawings 
of it as seen from the front and from one side, naming all the parts 
that can be seen. 

DISSECTION OF THE EYE. 

Material. — Dissecting boards, six inches by eight inches, preferably of 
dressed stuff, though pieces of shingles will serve. Dissecting set. Pieces of 
newspaper of the same size as the boards. Beef eyes. Each member of the 
class should have an eye to dissect. To supply a large class it is best to send 
to a slaughtering house in the nearest large city. If the external parts have 
already been studied, it will not be necessary to remove the muscles and th£ 
fat around the eye ; in fact, they may well be left undisturbed, since they 
serve as a cushion to support the eye during dissection. The dissection should 
be made on a piece of printed paper laid on a piece of board. When 
you wish to turn the eye, do so by turning the support, as the eye usually 
sticks to the support and the dissection may be injured by trying to move it. 



io8 PHYSIOLOGY. 

Caution. — After the eye is opened be careful not to compress 
it strongly. The jellylike contents may easily be squeezed out 
and the dissection ruined. Let the eye rest on the board all the 
time. 

i. Lay the eye on the paper-covered board, with the cornea 
uppermost. See that it rests firmly, propping it, if necessary, to 
keep it level. Hold the eye firmly with the thumb and fingers of 
one hand ; with the thumb and finger of the other hand hold the 
blade of the scalpel half an inch from the tip ; with a steady 
motion push the tip of the blade horizontally through the cornea, 
near its edge. 

2. The liquid in the cavity back of the cornea is the aqueous 
humor. 

3. Slightly enlarge the cut horizontally ; then with the forceps 
take hold of the upper edge of the cut, and with the scissors cut 
around the margin of the cornea and remove it. 

4. The dark membrane now exposed is the iris. Pinch the eye 
slightly at the sides to make the iris show more plainly. The 
hole in its center is the pupil. With the forceps raise the edge of 
the iris around the margin of the pupil to see that it is here unat- 
tached to the structures beneath it. Observe the color and mark- 
ings of the iris. 

5. From the end of the pupil cut outward to the outer margin 
of the iris ; then cut around its outer border and remove it. Note 
the color and markings of its inner surface. 

6. The body now laid bare is the crystalline lens. Touch it. 
Caution. — In the next operation do not press hard on the eye, 

or the lens may pop out suddenly. 

7. Gently press the sides of the eye with the thumb and finger, 
to raise the lens and hold it steady. Make a quick light gash 
with a sharp scalpel, or a quick light scratch with a needle, across 
the surface of the lens to cut through the thin lens capsule 
which incloses it. Do not let the lens tumble out before you 
have carefully compared its front and back surfaces. Which 
surface is more convex ? Usually the lens may be made to come 



EXTERNAL FEATURES AND STRUCTURE OF EYE 109 

part way out by gentle pressure on the sides of the eye. If not, 
enlarge the opening in the capsule and cautiously lift one 
edge of the lens with the handle of the scalpel. Now squeeze 
the eye to make the lens fall out on the paper, and look 
through it at the letters. Make a sketch of the lens as seen 
from the front, and as seen from the side, labeling the front and 
back surfaces. 

Caution. — In removing the front part of the eye as directed 
below, be careful not to drag out the clear, jellylike vitreous humor. 
The parts must be lifted gently and the vitreous humor must be 
cut entirely through with the scissors. 

8. Insert one blade of the forceps into the opening where the 
lens came out. Push this blade downward and outward close to 
the inside of the eye-coat till it pushes against the inside of the 
wall just above the widest part of the eye. Now shut the forceps 
strongly and push slightly so as to make the eye-coats bulge out- 
ward. With the scissors cut a small hole through the eye- coats 
just below the tips of the forceps. Insert one blade of the scissors 
in this hole and cut horizontally through the eye-coats, clear around 
the eye, meanwhile holding, with the forceps, the outer edge of the 
cornea above the point where the scissors are cutting. As you 
proceed, turn the board and be careful not to displace the anterior 
part of the eye. With the forceps take hold of the outer edge of 
the cornea and lift one side gently and steadily while cutting 
horizontally with the scissors through the jellylike vitreous humor, 
in the plane of the circular cut just made. Lay the front half of 
the eye, inside up, beside the back half. On its inner surface 
note the black radiating ridges, the ciliary processes. 

9. Carefully pick away with the forceps, and snip away with the 
scissors any of the black pigment or other matter on the surface 
of the clear mass beneath. This clear substance is the vitreous 
humor. 

10. Through the vitreous humor the entrance of the optic nerve 
may be seen with the blood tubes radiating from it. If necessary, 
carry the dissection to a window to let the light enter from above. 

11. The tough outer coat is the sclerotic coat. 



no PHYSIOLOGY. 

12. Inside the sclerotic is the dark choroid coat. 

13. The inner, nearly transparent, pinkish or whitish coat is the 
retina. At this stage of dissection it has probably become slightly 
wrinkled, showing white or pinkish ridges, often radiating from the 
optic nerve. 

14. Drag out the vitreous humor and examine the retina. What 
is its relation to the optic nerve ? Tear away the retina, noting its 
consistency. 

15. Note the color and luster of the inner surface of the 
choroid coat. It is said that this lustrous surface, with the dark 
(pigmented) inner layer of the choroid, is really part of the retina ; 
but it tears loose from the retina, adhering to the choroid coat. 

16. The reflection of light from this lustrous surface gives the 
light that we see in the eyes of some animals at night. 

17. Turn the remaining coats inside out and tear the choroid 
coat from the sclerotic. Observe the blood tubes passing from 
one to the other. 



CHAPTER XVI. 
THE ACTION OF THE EYE. 

INVERSION OF THE IMAGE BY A DOUBLE CONVEX LENS. 

Apparatus. — Double convex lens, such as a reading glass, burning glass, 
common pocket lens, or tripod magnifier. If possible, get two lenses, one 
decidedly more convex than the other. Sheet of white paper. Camera, with 
ground-glass focusing plate. 

i. Stand near the rear of a room, facing the window. Hold 
the lens vertically. Back of the lens hold a sheet of white paper, 
moving it forth and back till the image of the window is distinct 
on the paper. Can you see clearly that the image is inverted? 
While watching the image have some one pass in front of the 
window. Have the person stand near one edge of the window. 
In the image does he appear to be on the same side ? Is there 
inversion from right to left as well as up and down ? 

2. Hold side by side two lenses of different thickness. Can 
you get distinct images from both at the same time on the same 
paper? Which lens forms the image closer to the lens, the thicker 
or thinner ? 

3. If a lens could become thicker, would the image be nearer 
the lens, or farther away, than it now is? If a lens could become 
thinner, which way would its image move? 

4. Focus an image on the ground-glass plate of a camera. 
Note that it is inverted. 

5. How is a camera adjusted so that, whatever the distance of 
the object, the image is made distinct on the ground-glass plate? 
Can the eye be adjusted in the same way? 

6. What is the color of the inside of a camera? Why? 



112 PHYSIOLOGY. 

INVERSION OF THE IMAGE IN THE EYE. 

Material. — Fresh beef eye. Get this from a local butcher within an 
hour after the animal is killed; otherwise the cornea maybe opaque and the 
image will not be clear. Dissecting set. 

i. With sharp scalpel and scissors cut away about a quarter of 
an inch square of the sclerotic coat in the center of the back of the 
eye. Remember that the choroid coat and retina are very soft 
and delicate. Scrape away the choroid coat over the area where 
the sclerotic coat has been cut out. Hold the eye with the 
cornea facing a window, a lighted lamp, or other distinct object. 
If you do not see the image distinctly, exclude the outside light 
by placing the eye in the end of a tube made by rolling heavy 
paper. Can you see clearly that the image is inverted ? 

REGULATION OF THE AMOUNT OF LIGHT ADMITTED 
INTO THE EYE. 

Material. — Hand mirror. Cat. 

i. Hold a hand mirror between the face and a well-lighted 
window. Note the size of the pupils. Quickly turn toward the 
darkest part of the room. What change do you see in the pupils ? 
The iris has circular muscles that shorten and thus reduce the size 
of the pupil when there is too much light for the eye. When the 
light is feeble, the pupil opens wider. 

2. Why is the eye pained on coming from the dark into a 
bright light? How is it that one sees so poorly on going from a 
lighted room into the dark? Why can one see so much better 
after being in the dark awhile? 

3. How does the oculist dilate the pupil when he wishes to 
examine the inside of the eye? 

4. Watch the pupils of a cat's eyes in a bright light. Darken 
the room and again examine them. 

5. How do you explain the light seen in a cat's eyes in the 
dark ? Do eyes ever produce light ? 



THE ACTION OF THE EYE. 113 

ADJUSTMENT OF THE LENS FOR SEEING AT DIFFERENT 
DISTANCES (ACCOMMODATION). 

Material. — Book. Pins. 

1. Stick a pin into the edge of the cover at each end of a book. 
Hold the book at about the usual distance for reading, so that the 
two pins are in line with the eye. Look closely at the nearer pin 
and the second pin will appear indistinct. Now look closely at 
the head of the second pin. The nearer one may be seen, but not 
sharply distinct. These experiments show that the eye is not 
adjusted for seeing near and far objects at the same time. The 
adjustment is in changing the shape of the lens. This change is 
an involuntary one and takes place without our knowing it. It is 
not easy to prove its action. 

2. Another way of showing that some change must take place is 
this. Hold the tip of a pencil in line with any object, say a 
picture on a wall opposite. On looking at the tip of the pencil 
the picture is dim. Now look past the pencil at the picture and 
the tip of the pencil is blurred. 

3. Watch the pupil of another person's eye while he looks from 
a dimly lighted room at a distant object. Now hold a pencil a 
foot from his eyes and in direct line with the distant object. 
When he looks at the pencil, what change takes place in the pupil ? 

4. In this experiment the eyeball should not be moved in chang- 
ing from a far to a near object. Stand at one side and a little 
behind the observed person, so you can see the side of the eye. 
Have a near and a distant object in line with his eye. While he 
is looking at the distant object, note closely the degree of projec- 
tion of the pupil and iris, as seen through the side of the cornea. 
Now have him look at the nearer object. Do you see any change 
in the position of the iris? 

5. Hold a pencil erect about a foot in front of the eyes and in 
line with a door, person, or other large, distinct object, on the 
other side of the room. Look at the door. How many pencils 
do you see? Shut the right eye. Which one disappears? 



H4 PHYSIOLOGY. 

6. Now look at the pencil. How many doors do you see? 
Shut the right eye. Which door disappears? Can you explain 
these appearances? 

7. Watch the eyes of a person as the gaze changes from a far to 
a near object. Do you observe any change in the position of the 
eyes? 

8. Compare the upper and lower parts of the following figures 
and letters : 3, 3, 3, 3, 3 ; 8, 8, 8, 8, 8 ; S, S, S, S, S. Are the 
parts equal? Invert the paper and look at them. 

APPARATUS ILLUSTRATING THE CHANGES IN THE LENS 
DURING ACCOMMODATION. 

Material. — Glass globe (globe aquarium) or rose jar, eight or ten inches 
in diameter. Rubber balloon, "squawker," or "pillow dex." Muslin bag, 
three inches square. Rubber bands, either the cloth-covered elastics or 
"sling-shot" rubbers. Safety pins. String. Needle and thread. Instead 
of balloon, a football bladder, with large cloth bag, or a common pillow, will 
do fairly well. 

i. Insert the balloon in the bag, inflate, and tie it. Lay the bag 
on the inverted glass globe. Fasten a rubber band to one corner 
of the bag, pass it clear around under the globe, and attach it to the 
opposite corner of the bag, with a fair degree of tension. Connect 
the other two corners by a similar band, which crosses the first at 
right angles, under the jar. Fasten the bands at their crossing so 
they will not slip. The tension of the bands should flatten the 
balloon. 

2. The balloon represents the lens, which is elastic and rather 
thick when not compressed. The cloth bag represents the lens 
capsule. The tension of the rubber bands corresponds to the 
tension of the suspensory ligament. This tension, applied to the 
lens capsule, flattens the lens. This flattened shape represents 
the lens in the resting eye, and when adjusted for seeing distant 
objects. 

3. Attach a cord to each rubber band close to the corners of 
the bag. Hold the cords from two adjacent corners in one hand, 



THE ACTION OF THE EYE. 115 

the other two in the other hand. Pull on all four cords toward a 
central point three or four inches above the bag. This releases 
the tension of the rubber bands on the bag, and, through the bag, 
on the balloon. The elasticity of the balloon makes it thicken and 
bulge up. 

4. The pull of these cords, toward the center, represents the 
action of the ciliary muscle pulling toward the lens. The ciliary 
muscle is attached around the border of the cornea, and when it 
shortens, it pulls the suspensory ligament forward, diminishing its 
tension on the lens capsule. The elasticity of the lens causes it 
to thicken, thus accommodating itself for near vision. 

5. A common pillow may be used to illustrate this action. Lay 
the pillow on a small table. Attach to each corner of the pillow 
case a weight of ten or more pounds, the weight hanging over the 
edge of the table. These should be so adjusted as to flatten the 
pillow. Cords attached to the corners, when pulled toward a 
point above the pillow, will overcome the tension produced by the 
weights and the pillow will bulge upward. A football bladder 
may also be used, following about the same general plan. The 
size of the apparatus should be adapted to the size of the class or 
room. 

THE BLIND SPOT. 

1. At the left (as looked at by the class) of a long blackboard, 
make a bright spot, three inches in diameter, with white or yellow 
crayon. Beginning at the right of the spot write the figures 1, 2, 
3, 4, etc., at intervals of about eight inches along the whole length 
of the board. 

2. Let each pupil close the right eye and look at the bright 
spot. Then read the figures, passing slowly from one to another, 
at the same time noticing whether the spot can still be seen. To 
succeed, the eye must not be allowed to waver. When looking at 
a given figure the eye must be fixed firmly on it. Have the 
pupils tell when the spot disappears. Then let them read on till 
the spot appears again. 



n6 PHYSIOLOGY. 

3. In the following experiment, shut the right eye and be care- 
ful not to let the left eye waver. 

jf Read this line slowly. Can you see the star all the time? If 
the star does not disappear before reaching the end of the 
line, let the eye travel on across the right-hand page or hold the 
book nearer the face. Does the star reappear? 

4. In the human eye the optic nerve enters the eye, not in the 
center, but nearer the nose. So, when one turns the left eye 
toward the right at the proper angle, the image of the star falls 
upon the spot where the optic nerve enters. As this spot is 
insensitive to light, the star no longer appears. 

DURATION OF IMPRESSIONS OF LIGHT. AFTER-IMAGES. 

Apparatus. — Lamp. The first three are evening experiments. 

i. For five minutes sit facing a lighted lamp, but with the eyes 
closed and shaded. Suddenly open the eyes and close them 
immediately. The lingering appearance of the lamp is called the 
positive after-image. It shows that the sensation lasts longer than 
merely while the light directly stimulates the eye. 

2. Rapidly whirl a stick with a glowing coal on the end. The 
continuous streak of light shows the duration of the impression. 

3. Look steadily at a lamp for half a minute, then close the 
eyes. Do you get the positive after-image? If you see the lamp 
in black, you have the negative after-image. Do you get both the 
positive and the negative after-images in the same experiment? 
If so, which appears first? 

4. Sit facing a window strongly lighted by sunlight. Look 
steadily at the window till the eye begins to feel tired. Then 
quickly close the eyes, or look toward a white wall or ceiling. 
What do you see ? 

5 . Look at a rapidly revolving wheel. Why do the spokes blur 
together? While facing a revolving wheel, close the eyes for a 
minute. Quickly open and shut them. Do you now see the 
spokes distinctly? Explain. 



THE ACTION OF THE EYE. 117 

COLORED AFTER-IMAGES. 

Material. — Red, blue, green, and yellow seals, an inch or more in diam- 
eter. White cardboards, four inches by six inches. 

1. Paste one seal on each cardboard, halfway between the 
middle and one end. Halfway between the middle and the other 
end make a small distinct black spot. Make a distinct black spot 
in the center of the seal. 

2. Take a card with a red seal. Look steadily at the dot in 
the center of the seal till the eyes begin to tire. Then look 
quickly at the dot on the white part of the cardboard. What 
color do you see ? What relation has this color to the color of 
the seal? 

3. Repeat experiment 2 with all the colored seals. Vary the 
experiment thus : instead of looking away, when the eyes begin to 
tire, quickly slip a white paper over the seal. Or look up quickly 
at a white wall or ceiling. 

TEST FOR COLOR-BLINDNESS. 
Material. — Skeins of worsted of all colors and shades. 

1. Select a light green skein. The person tested is to select 
quickly all the other skeins that are of the same color as the 
sample. He is not to name the colors, but simply to lay aside all 
that he considers of the same color as the sample. Of course 
this test should be wholly free from any aid or suggestion. 

2. In the same manner have him pick out all colors that match 
a red skein that you have selected. Compare the results of these 
experiments with any statements that you find in the text-books. 

3. In the same way match a purple skein. 

4. What per cent of the class show a noticeable failure in match- 
ing colors ? 



CHAPTER XVII. 
THE EAR. 

DISSECTION OF THE EAR. 

Material. — Besides the regular dissecting set there will be needed a 
small pair of bone forceps and a pair of fine scissors. Watchmaker's glass. 
Knitting needle. Cat or rabbit. Kill the animal as directed on p. 41 and cut off 
the head at the base of the skull. 

i. Feel of the ear. Pinch it together and note the slight stiff- 
ness due to the cartilage. 

2. Examine the inside of the ear. Note the various folds and 
projections of its inner surface. " 

3. Beginning behind, slit the skin along the top of the head in 
the middle line to the tip of the nose. Loosen the skin on one 
side. Observe the flattish muscle running outward to the base of 
the ear. When this muscle shortens, how does it move the ear? 

4. From the angle of the mouth cut through the skin backward 
along the side to the base of the neck. Loosen the whole flap of 
skin above the last cut and look for other muscles that move the 
ear. Remove all the skin from the head. 

5. Cut off the ear cartilage as close to the bone as possible. Be- 
low and back of the opening observe a bulging hollow bone, the 
bulla. Cut away the muscle and other soft tissues covering it. 

6. Unhinge the lower jaw and cut it away, removing with it as 
much muscle as possible. Remove also the eyes and all soft 
tissues from the eye socket. 

7. Look through the ear opening into the cavity of the bulla. 
By turning the head at the proper angle in reference to the light, 
a thin, transparent membrane may be seen extending obliquely 
across the cavity within. This is the tympanic membrane or drum 

118 



THE EAR. 119 

skin. It is so delicate that one is likely to look through it without 
detecting it, unless he catches the reflection of light from its 
surface. 

8. Attached to the inner surface of the drum skin, and showing 
clearly through it, is a slender white bone, the hammer, or malleus. 

(In the following dissection the head is to be held upside down. 
The words " up " and " down " will have reference to this position. 
That is, up means toward the base of the skull and down means 
toward the crown.) 

9. Hold the head with the bulla uppermost. With a light pair 
of bone forceps carefully cut through the most prominent part of 
the bulla. The cavity is the tympanic cavity, or middle ear. 
Observe that it is lined by a thin, transparent membrane. 

10. In the outer and posterior part of the cavity is a projection 
of pinkish bone. In this bony projection note a circular depres- 
sion, the round window (fenestra rotunda). 

n. Observe a thin, convex, bony partition which shuts off a view 
of the drum skin. This partition divides the tympanic cavity into 
two parts, which communicate by a passageway near the outer pos- 
terior end, just over the round window. 

12. With the bone forceps carefully chip away this partition 
down to the pinkish bone above noted. Now examine the inner 
surface of the drum skin. Observe that.it is funnel shaped and 
that the handle of the hammer is attached to its inner surface. 

(In the remaining dissection it is advantageous to use a watchr 
maker's glass so that the parts may be seen without interrupting 
the dissection by stopping to pick up a lens.) 

13. With fine scissors cut through the attachment of the drum- 
skin along its upper and posterior border. With a small pair of 
bone, forceps cut away the upper part of the bony ring to which 
the drum skin was attached. 

14. The following parts of the hammer should now be seen ; (1) 
the handle, still attached to the inner surface of the drum skin ; 
(2) the head, extending downward and outward to form a joint 
with the anvil ; (3) the slender process, extending from the under 



120 PHYSIOLOGY. 

side of the head, and running down to the lower edge of the 
drum skin. 

1 5 . From the outer part of the tympanic cavity observe a white 
cord running to the front border of the bony rim surrounding the 
round window. From the inner end of this cord a fine thread 
extends to the head of the hammer. This is the posterior ligament 
of the hammer. 

1 6. From the under side of the head of the hammer there 
extends downward and inward a tiny, white, bony projection. At 
its tip is attached a cone-shaped pink muscle, the tensor tympani 
muscle. With a knitting needle, or blunt wire, press down on the 
tensor tympani muscle and note that it tightens the drum skin. 

17. With fine scissors very carefully sever the posterior ligament. 
Also cut around and remove as much as possible of the drum skin. 
Be especially careful to avoid breaking the " slender process " of 
the head of the hammer. With a small pair of bone forceps care- 
fully chip away the outer wall of the tympanic cavity. 

18. Note a projection from the anvil running upward and inward, 
nearly parallel to the head of the hammer. Its upper end joins 
the head of the stirrup. Note the fork between the side pieces of 
the stirrup as they extend downward to the foot of the stirrup. 
The foot of the stirrup is lodged in an oval depression, the oval 
window (fenestra ovalis) . Across this window is stretched a thin 
membrane, and to this thin membrane the foot of the stirrup is 
attached. Beyond this membrane is the vestibule. 

19. Observe the fine, slender stapedius muscle, extending from 
behind to be attached to the head of the stirrup. 

20. Cut away the arch of the cheek bone and, proceeding 
cautiously backward, chip away still more of the outer wall of the 
tympanic cavity. Observe that the anvil has a second projection, 
extending nearly straight backward to be attached to the bony 
wall. 

21. At the outer end of the " slender process " of the hammer, 
carefully sever its attachment to the bony wall. With fine scissors 
cut the tensor tympani muscle close to the bony projection of the 



THE EAR. 121 

head of the hammer. In the same way cut between the head of 
the stirrup and the tip of the upper arm of the anvil. Carefully 
remove the hammer and anvil. Find how the two are joined. 
Very carefully cut around the base of the stirrup and remove it. 

22. Arrange the three ear bones as nearly as possible in their 
natural relations, fasten them to a black card by means of glue, and 
preserve in any suitable, glass-covered case. An old watch case 
makes a good case. 

23. At the front and inner end of the cavity is the opening of 
the eustachian tube. It disappears under a little projecting shelf 
of bone. Pass a bristle into it and note where it enters the 
pharynx. 

24. Probe the " round window " with a sharp instrument to prove 
that it is closed by a thin membrane. With fine bone forceps cut 
away the bone around the "round window." Proceed downward 
and inward to find the coils of the snail shell or cochlea. At its 
base find the auditory nerve. 

25. The semicircular canals may be traced by carefully chipping 
away the very brittle bone in which they lie. In tracing them, 
follow the descriptions and figures in any of the larger works on 
anatomy. 



CHAPTER XVIII. 
THE VOICE. 

DISSECTION OF THE LARYNX. 

Material. — Larynx of a calf, sheep, or hog. Dissecting set. 

i. The front of the larynx is readily distinguished by the projec- 
tion of cartilage known as Adam's apple. 

2. Along the back of the larynx runs a thick, muscular tube, 
the gullet, or esophagus. 

3. The cartilage forming the greater part of the front of the 
larynx is the thyroid cartilage. 

4. Observe the band of muscle attached to either side of the 
thyroid cartilage and passing horizontally back around the gullet. 
Cut away and remove this muscle and the gullet. Note that the 
whitish mucous membrane which lines the gullet is continuous with 
the lining of the larynx. Study now more fully the shape of the 
thyroid cartilage. 

5. Back of the upper part of the thyroid cartilage, covering the 
upper end of the larynx, is the arched epiglottis. Feel of it to 
learn its consistency. Press it upward and forward, then down- 
ward and backward. Observe that when pushed back it covers the 
entrance to the larynx. Note what position it takes when released. 

6. Just back of the upper angle of the thyroid cartilage find a 
muscle connected with the base of the epiglottis. Pull this muscle 
to determine what effect its shortening has on the epiglottis. 

7. Under the thyroid cartilage in front observe a narrow ring 
of cartilage not much wider than one of the rings of the windpipe. 
Move this ring up and down to prove that it is distinct from the 
thyroid. It is the cricoid cartilage. 



THE VOICE. 123 

8. Observe the thin crico-thyroid muscle, passing from the 
cricoid to the thyroid. Again move the cricoid toward and from 
the thyroid ; what does this muscle do ? Cut away this muscle 
from one side, and see that the cricoid cartilage widens as it 
passes backward. How are the cricoid and thyroid hinged 
together? 

9. Projecting upward and backward from the top of the larynx 
are two curved yellowish cartilages, the arytenoid cartilages. Prove 
that they are movable, and that they rest on the upper edge of the 
back part of the cricoid cartilage. 

10. Move the arytenoid cartilages backward and forward, 
meanwhile watching the inside of the larynx from its lower open- 
ing. The projecting ridges, which meet just back of the Adam's 
apple, are the vocal cords. What effect is produced on the vocal 
cords by the movements of the arytenoid cartilages ? 

n. Observe the connection of the thyroid cartilage with the 
cricoid by means of a downward projection of the former. Cut 
away all of this half of the thyroid cartilage. Notice the slen- 
der hyoid bone loosely connected with the upper horn of the 
thyroid. 

12. Examine now the muscles which move the arytenoid 
cartilages : 

(a) On each side of the posterior surface of the cricoid is a 
muscle passing upward to be attached to the corresponding aryt- 
enoid; this is the posterior crico- arytenoid muscle. Dissect it 
loose from the cricoid at its origin below. By pulling, determine 
its action on the arytenoid, and through the arytenoid, on the 
vocal cords. 

(b) Arising from the upper edge of the side of the cricoid car- 
tilage, and passing upward and backward to the arytenoid, is the 
lateral crico-arytenoid muscle ; cut it away at its origin, close to 
the cricoid, and demonstrate its action on the arytenoid cartilage 
and vocal cord. 

(c) A broad muscle arises along the whole length of the angle 
of the thyroid ; this is the thyro-arytenoid muscle ; cut it across 



124 PHYSIOLOGY. 

near its origin, dissect it loose, and prove its action by pulling it 
toward its origin. 

(//) On the posterior surface of the arytenoid is the small 
arytenoid muscle. 

13. Cut between the arytenoid cartilages and remove one of 
them. Examine the joint between the arytenoid and cricoid. 
Note the synovia lubricating the joint. 

14. Trim away the muscle from the arytenoid cartilage and 
study its shape more fully. Fit it again to its place, and recall 
the motions given by each muscle. 

15. Now examine the arytenoid cartilage and the vocal cord 
of the opposite side ; move the arytenoid forth and back, watching 
the vocal cords. 

16. Remove the epiglottis, and cut into it to see its structure. 

17. Dissect away the parts of the other side of the larynx from 
the inside, reviewing the above points. 

STUDY OF THE HUMAN LARYNX. 

Apparatus. — Dentist's mirror. Hand mirror. Borrow a laryngoscope 
and head mirror of a doctor and ask him to show you how to use it. 

i. Place the fingers on the Adam's apple. This is a projecting 
angle of the thyroid cartilage. Feel the ridge extending down- 
ward from the Adam's apple. This is also part of the thyroid 
cartilage. 

2. Place the tip of the finger in the depression just above the 
Adam's apple. The transverse ridge just above this is the hyoid 
bone. Now perform the act of swallowing. What change in the 
position of the larynx ? What change in the relation of the thyroid 
cartilage and the hyoid bone? 

3. Below the thyroid cartilage feel the narrower cricoid cartilage. 

4. Below the cricoid cartilage feel the windpipe, with its rings 
of cartilage. 

5. Direct strong light into the back of the mouth with a 
dentist's mirror or a laryngoscope. Examine the part, of the 



THE VOICE. 125 

pharynx back of the base of the tongue. Observe the epiglottis, 
standing nearly erect, close to the tongue. 

6. Back of the epiglottis is the glottis, or opening leading from 
the pharynx to the larynx. 

7. Farther down are the vocal cords, appearing like transverse 
ridges, extending horizontally from the sides of the larynx, partly 
obstructing the air passages. Let the person examined sing "ha" 
up and down the scale. What changes do you see in the vocal 
cords ? 

APPARATUS ILLUSTRATING THE VOCAL CORDS. 
Apparatus. — Toy squawkers. Mirror. 

1. Inflate a squawker and remove it from the mouth to see that 
it squawks properly. 

2. Remove the balloon and note the band of rubber across the 
end of the tube. Stand before a mirror and suck through the 
tube. What is the condition of the rubber during the production 
of the sound? 

3. Remove the rubber band and put on two bands, one project- 
ing from each side, leaving a narrow slit in the middle. Can you 
produce sound by the vibration of the two membranes? 

THE USE OF THE ORGANS OF SPEECH. 

1. Pronounce the vowels. Note the positions of the lips and the 
tongue and the shape of the mouth as each sound is made. 
Which vowel sound requires the most open condition of the mouth 
and throat? Which the narrowest? Are all the vowels simple 
sounds? Pronounce " i " slowly. Of what parts is it composed? 

2. Pronounce the consonants in order, noting the conditions 
and relative positions of the lips, teeth, and tongue as each conso- 
nant is produced. 

3. What consonants require the closing of the lips? What is 
the difference between "b " and "p"? 

4. In forming what consonants does the tongue touch the teeth? 



126 PHYSIOLOGY. 

5. In what consonants does it touch the palate ? Compare "t" 
and " d." 

6. How is " s " produced? 

7. How do we make the " h " ? 

8. Explain the "k" sound. Compare it with "g" hard. 

9. Compare " f " and "v." 

10. What kind of sound is " w " ? 

1 1 . What consonants are most likely to be mistaken one for the 
other? Why? 



CHAPTER XIX. 

THE SKELETON. 

THE SKELETON AS A WHOLE. 
Material. — Mounted human skeleton. 

i. Observe that the skeleton as a whole consists of two portions, 
the axial portion and the appendicular portion. The axial portion 
consists of the central axis, the spinal column, of which the head 
may be regarded as a part. The appendicular portion consists of 
the limbs and the bones belonging to them. 

2. In the skeleton as a whole observe : (a) the skeleton shows 
the form of the body ; (b) it supports the softer tissues ; (c) it 
protects softer parts, as the brain in the skull, the spinal cord in the 
spinal column, the heart and lungs in the thorax, etc ; (d) the 
bones serve as levers in producing motion and locomotion. 

STUDY OF A THORACIC VERTEBRA. 
Material. — Mounted skeleton. Separate vertebras. 

i. Take a vertebra from the middle of the spinal column : {a) 
its most solid part is its body or centrum ; (b) on the dorsal side 
of this is the neural arch, forming with the body the neural ring, 
through which the spinal cord passed ; (V) from this arch there 
extend projections, or processes. 

2. Hold the vertebra by the tip of its longest process, and 
place it beside the corresponding vertebra in the complete skele- 
ton. Note that (a) the body is flattened where it fitted against 
the vertebras anterior and posterior to it ; (b) the holes in the 
vertebras form a passage for the spinal cord ; (c) the middle pro- 

127 



128 PHYSIOLOGY. 

cess is the spinous process, and the series of spinous processes 
form the ridge of the backbone ; (d) the two lateral processes are 
called the transverse processes. 

3. Fit together two vertebras in their proper order and observe 
that : (a) the openings at the sides, through which the spinal 
nerves passed, are formed by adjacent notches, or grooves, in the 
contiguous vertebras ; (b) the two projections extending anteriorly 
from the ring of one vertebra fit against two corresponding pro- 
cesses extending posteriorly from the other vertebra. These are 
the anterior and posterior articulating processes. 

4. Each vertebra, then, has seven processes, four articulating 
(two anterior and two posterior), two transverse, and one spinous. 
The smooth places where the articulating processes join are called 
facets. Observe on each side of the body of the vertebra a facet 
where the head of the rib articulated. There is also a facet on the 
transverse process where the tubercle of the rib articulated with it. 



STUDY OF THE SPINAL COLUMN. 
Material. — Mounted skeleton and separate vertebras. Bone forceps. 

1. The first vertebra, the atlas, has no body. The second ver- 
tebra is the axis. It has a peg, called the odontoid process, which 
represents the body of the atlas. In shaking the head the atlas, 
with the head, turns on the axis. In nodding the head, the head 
simply rocks forth and back on the atlas. 

2. The seven cervical vertebras (neck) have holes through their 
sides, or transverse processes, for the passage of blood tubes. 

3. The twelve rib-supporting vertebras are the thoracic 
vertebras. 

4. The next five are the lumbar vertebras. The sacrum is 
composed of five vertebras grown together; they form a solid 
block, to which the bones of the pelvis are attached. 

5. The remaining four vertebras are combined to form the 
coccyx. 



THE SKELETON. 129 

6. Let the eye slowly review the whole spinal column, noting 
what all the vertebras have in common. Note also their dif- 
ferences. 

7. In most articulated skeletons there are pads of felt between 
the vertebras. These take the place of the intervertebral cartilages, 
which are a form of connective tissue, possessing the elasticity of 
cartilage and the toughness of fibrous connective tissue, such as 
ligaments and tendons. These intervertebral cartilages serve both 
to keep the vertebras apart and to hold them together. When 
we bend the shoulders to the right, the right edges of these car- 
tilages are compressed, and the left edges are stretched, as a piece 
of rubber would be if it were glued between the ends of two 
spools, and the whole were slightly bent. 

8. View the spinal column from the side. Draw a line repre- 
senting all its curves. 

9. Take a thoracic vertebra, and in the presence of the class, 
trim off the processes with a pair of bone forceps. The vertebra 
will then be seen to be, essentially, like a ring or padlock. 

STUDY OF THE SKULL. 
Material. — Human skull. 

1. Note the irregular line of union between the larger bones of 
the cranium. These joints are called sutures. 

2. Can you distinguish the frontal, occipital (back), and the 
two (side) parietal bones? 

3. Examine the nasal passages. 

4. How is the lower jaw joined to the skull? 

5. If you have a skull that is sawed in two, note the size of the 
brain cavity. Compare the inner and outer surfaces of the cranial 
bones. 

6. The large hole at the base is for the passage of the spinal 
cord. 

7. In the base of the cranial cavity note the holes for the pas- 
sage of the cranial nerves and blood tubes. 



130 PHYSIOLOGY. 

STUDY OF THE BONES OF THE THORAX. 

Material. — Mounted human skeleton. 

i. Observe that the chest cavity is conical while the chest as a 
whole is an inverted cone, owing to the projecting bones at the 
shoulders. 

2. Note that the ventral ends of the ribs are joined to the 
breastbone by cartilages. These are called the costal cartilages. 

3. With what bones does each rib join? 

4. Study the movements of the ribs and breastbone in breath- 
ing. With this observation fresh in mind again study the joints 
and general structure of the chest. 

5. To what extent is each upper limb jointed with the rest of 
the skeleton? 

STUDY OF THE BONES OF THE ARM. 
Material. — Bones of the arm, preferably of an articulated skeleton. 

i. Rest the forearm on the table with the palm upward ; keep- 
ing the elbow fixed, turn the hand over. Turning the palm up is 
called supination ; turning it down is called pronation. 

2. Repeat these acts with the jointed bones of the forearm. 
Notice closely the relations of the radius and ulna in each posi- 
tion. 

THE BONES OF THE LOWER LIMBS. 

Material. — Skeleton and separate bones of the lower limbs. 

1. In your own body study the range of motion at the hip. 
Then examine the hip joint of the skeleton. It is a ball-and- 
socket joint. 

2. In the same way compare the live knee with that of the 
skeleton. It is a hinge joint. When the lower limb is extended, 
take hold of the kneecap and study its range of motion. 

3. Examine the ankle joint in the skeleton and compare with 
the movements of your own ankle. 



THE SKELETON. 131 

MICROSCOPIC STRUCTURE OF BONE. 
Material. — Prepared slide with cross section of bone. Microscope. 

1. Hold a mounted cross section of bone up to the light and 
examine it with a hand lens. The solid part of the bone will be 
seen to be pierced by many small holes, or if the holes are filled, 
they will appear as black spots. These are the cross sections of 
the haversian canals, through which ran the blood tubes, mainly 
lengthwise through the bone. 

2. Examine the section under the microscope, using a two-thirds 
inch objective. The bony matter will now be seen to be arranged 
in circles, lamellas, around the haversian canals, somewhat like the 
rings seen on the end of a log. 

3. Between the rings are circles of elongated dark dots. These 
are the lacunas, cavities in which lay the bone corpuscles which 
built up the bone. The bone was, at first, cartilage. Later 
mineral matter was deposited, forming true bone. 

4. Now examine the section under a one-sixth inch objective. 
From the lacunas there run out, in every direction, little crevices, 
the canalicules, appearing as fine black lines. Through the haver- 
sian canals, lacunas, and canalicules the nourishing materials of the 
blood reach all parts of the bone. 

THE CHEMICAL COMPOSITION OF BONE. 

Material. — Dry rib of sheep. Tall, narrow jar (graduate) or straight 
lamp chimney corked at one end. Hydrochloric acid. 

i. Nearly fill a tall jar with water. Add one sixth as much 
hydrochloric acid. Put into this a slender dry bone, such as a rib 
of a sheep. In twenty-four hours take it out, rinse it thoroughly, 
and examine it. The acid will probably have dissolved out the 
mineral matter and left the animal matter. 

2. Lay a piece of bone on a shovel, or piece of sheet iron, and 
place it in the fire. The animal matter is burned out, leaving the 



132 PHYSIOLOGY. 

brittle mineral matter. Bone is composed of mineral matter, two 
thirds, and animal matter, one third. In childhood the animal 
matter is in larger proportion, while in old age the mineral matter 
is in excess. The mineral matter is chiefly calcium phosphate, 
while the animal matter is largely gelatin. 



CHAPTER XX. 
YEAST AND BACTERIA. 

THE ACTION OF YEAST. FERMENTATION. 

Material. — A- cake of compressed yeast. Lime water. Thermometer. 
Two pint bottles. Three four-ounce bottles. Molasses. Tumbler. Ice or 
refrigerator. Test tubes. Spray bulb. Glass tube, three inches long, of the 
diameter of a lead pencil. 

i. Pour half an inch of water into a tumbler. Into this put 
about an eighth of a cake of compressed yeast, and stir till it is 
thoroughly mixed with the water. Half fill a pint jar or bottle with 
water. Add a tablespoonful of molasses and stir till it is well 
dissolved. Add the yeast to this and set the bottle where the 
temperature is 70 F., or more. Note the smell and taste of the 
liquid. 

2. After a few hours examine the liquid to see if any change has 
taken place. If some change is taking place, pour some of the 
liquid into each of two small bottles. Place one (1) bottle on ice, 
or in a refrigerator. Place a second (2) bottle in a temperature 
of 70 F. to 8o° F. Boil a small quantity of the same yeast from 
the larger bottle and pour it into a third small bottle. Set this in 
a warm place with bottle number 2. Label, " 3, Boiled yeast." 

3. How is the yeast in the chilled bottle affected? After it has 
been in the refrigerator ten or twelve hours, put it in a warm place, 
with numbers 2 and 3. Does any change now take place? What 
difference in the permanence of the effects of boiling and chilling ? 

4. Place bottles of yeast in various temperatures from 50 F. 
to 150 F. At about what temperature is fermentation most 
active ? 

133 



134 PHYSIOLOGY. 

5. After the yeast has been actively "working," how does it 
smell and taste? Compare the results with those of experiment 1. 

6. Loosely stopper a bottle in which yeast is working. Test the 
gas in the bottle above the yeast as follows : Get a spray bulb and 
insert a glass tube three inches long and of the diameter of a lead 
pencil. With this suck out the gas above the fermenting liquid 
and force it through a little lime water in a tumbler. If the lime 
water becomes milky, it shows the presence of carbon dioxid. 

7. If a distilling apparatus can be obtained (from the physical 
laboratory), distil the liquid left after fermentation, at a tempera- 
ture of about 1 75 F. This experiment should prove that alcohol is 
produced by the action of yeast. 

8. Place yeast in pure (distilled) water in a favorable tempera- 
ture. Does fermentation occur? How do you account for the 
results ? 

9. If yeast is used at home in bread making, carefully study the 
conditions in which it is placed. Compare with the above 
experiments. 

STRUCTURE AND GROWTH OF YEAST. 

Material. — Microscope. Slides and cover glasses. Eosin. 

i. Place a drop of active yeast on a slide. Cover and examine 
with a high power. The oval or elliptical bodies are yeast plants. 
Each consists of a single cell, having a thin, transparent wall, 
with liquid contents. 

2. Do you find, here and there, two or more cells united? Are 
they all of the same size? New yeast cells are formed as buds 
growing out of older cells. When they reach full size, they easily 
separate. How many do you find in any group? Actively shake 
a bottle of fermenting yeast. Examine a drop of this. Do you 
find any difference if you " shake before taking "? Why is this? 

3. Sketch a group of yeast cells, showing their mode of growth. 

4. Put a drop of eosin on the slide at the edge of the cover 
glass. Study closely the structure of the stained yeast cells. 



YEAST AND BACTERIA. 135 

BACTERIA. 

CLEANING AND STERILIZING FLASKS AND PETRI DISHES. 

Material and Apparatus. — Soap. Clean dish towels. Hot-air sterilizer 
(or gas or gasoline oven). 

1. Wash the dishes thoroughly with soap and hot water. Rinse 
in hot water and drain. Wipe the outside. 

2. After they are dry plug the flasks with absorbent cotton, 
cover the Petri dishes and place them in the hot-air sterilizer or 
gas oven. Raise the temperature to 150 C. and keep at this 
temperature for an hour. Turn off the heat, and when the tem- 
perature falls to 50 C, remove the dishes. Keep the flasks 
plugged and the Petri dishes covered till used. 

PREPARATION OF NUTRIENT GELATIN. 

Material and Apparatus. — Lean beef, 1 pound; sheet gelatin, 60 grams; 
salt, 6 grams ; peptone, 6 grams; sodium carbonate ; litmus paper; an egg. 
Earthen or granite ware bowl; granite ware double cooker; funnel and filter 
paper ; stirring rod ; sterilized and plugged flasks ; water bath. 

i. Remove all fat from the beef and grind or mince it fine. 
Place it in a bowl, pour a pint of water on it, and let it stand over- 
night. 

2. Filter through cheese cloth and add water enough to make 
600 c.c. Now add 60 grams of gelatin cut into small pieces, 
6 grams of peptone, and 6 grams of salt. 

3. Heat for an hour in a double cooker, but do not bring to a 
boil. 

4. Add sodium carbonate till it barely turns red litmus paper 
blue. 

5. Boil half an hour, stir in the white of an egg, and boil twenty 
minutes longer. 

6. Prepare a filter in the usual way and pour boiling water over 
the filter paper and funnel. Now filter the hot gelatin into 
sterilized flasks. 



136 PHYSIOLOGY. 

7. Boil the gelatin in a water bath for thirty minutes and care- 
fully plug the flasks with absorbent cotton. If the gelatin does 
not become turbid in a few days, it may be considered sterile ; 
when gelatin is needed, first liquefy it by placing the flask in the 
hot-water bath. 

PUTREFACTION. 

Material and Apparatus. — Handful of hay. Three glass flasks. One 
cork to fit flask. Funnel and filter paper. Absorbent cotton. Microscope. 
Granite ware basin. 

1. Pour hot water on the hay in a basin; let it stand a few hours 
and then filter it. 

2. Pour 100 c.c. of the infusion into a flask and boil for an hour. 
Turn off the heat and immediately cork the flask. 

3. Do the same with another flask, but plug with absorbent 
cotton. 

4. Repeat with the third flask, but let it stand unstoppered. 

5. Set the three flasks side by side in a warm room and 
watch them for several days. How do you account for the 
differences ? 

6. Examine a drop from flask number 3 under a high power 
(one sixth, or higher, if possible). Compare what you see with 
the figures and descriptions of bacteria. 

CONDITIONS REQUISITE FOR THE GROWTH OF BACTERIA. 

Material and Apparatus. — Fresh milk, one pint. Refrigerator or ice. 
Absorbent cotton. Bunsen burner. Nutrient gelatin. Three sterilized Petri 
dishes. Three sterilized flasks. Two corks to fit the flasks. The corks should 
be kept submerged in boiling water for twenty minutes. 

1. Pour 100 c.c. of milk into each of the flasks and cork two 
of them. 

2. Keep one corked flask at the ordinary temperature of the 
room. 

3. Place a corked flask in the refrigerator or on ice. 



BACTERIA. 137 

4. Boil the milk in the third flask for thirty minutes, plug with 
the cotton, and set it with the first flask. Label it, " Boiled milk." 
Watch and compare the flasks for a few days. 

5. After a few days take the flask from the refrigerator and set 
it beside others. Has the cold killed the bacteria? 

6. Pour 10 c.c. of gelatin into a sterilized Petri dish, expose 
to the air two minutes. Cover and set it in a shaded place. 
Do the bacteria have any effect on the gelatin? 

7. Prepare as in experiment 6, but place the dish in full sun- 
light. Compare with experiment 6. 

8. Prepare as in experiment 6, but leave the dish uncovered 
in dry air for several days. Do bacteria grow well without moisture ? 

9. What conditions are requisite for the growth of bacteria? 
10. What makes food spoil? Name the various methods of 

preserving foods. How is each of these methods effective ? 

BACTERIA IN AIR, DUST, MILK, WATER, AND ICE. 

Material and Apparatus. — Milk, one fourth pint. Ice, natural and 
manufactured. Six Petri dishes. Nutrient gelatin. Set the gelatin flask in a 
hot-water bath and warm it till it can be poured. Do not expose the material 
in the flasks and dishes longer than is necessary ; quickly recap the dishes 
and replug the flasks. Microscope. 

i. Pour 10 c.c. of gelatin into a sterilized Petri dish and leave 
it uncovered one minute. Cover and label it, " Gelatin, exposed 
to air one minute." Keep at a temperature of about 70 F. and 
watch for several days. 

2. In another dish place 10 c.c. of gelatin and sift over it a 
little dust from the top of a book or shelf. Cover and label 
" Gelatin and dust." Keep at about 70 F. 

3. To 10 c.c. of gelatin add 2 c.c. of milk. Cover and keep as 
above. 

4. To 10 c.c. of gelatin add 4 c.c. of your drinking water. 
Keep as before. 

5. Repeat, with the exception of using natural ice, half a cubic 
inch. 



138 PHYSIOLOGY. 

6. Repeat with manufactured ice. 

7. Each spot of the growth is a " colony " of bacteria and each 
colony is usually due to the growth of a single bacterium. Can 
you make an estimate as to the number of bacteria in a given 
quantity of any of the materials used in the above experiments ? 

8. With a needle transfer some of the material from a colony 
of bacteria to a glass slide. Add a drop of water. Cover and 
examine under a high-power objective. 

STERILIZATION AND PASTEURIZATION OF MILK. 

Material and Apparatus. — Two flasks of milk. Absorbent cotton. 
Thermometer. Retort stand. Bunsen burner. Double cooker. 

1 . Boil the milk in one flask for half an hour. 

2. Plug the other flask with absorbent cotton and set it in the 
double cooker. Fill the inner kettle with water above the level 
of the milk in the flask. Set the thermometer beside the flask. 
Heat till the water around the milk reaches 160 F. Shut off the 
heat and keep the cooker covered with a folded blanket or quilt 
for half an hour. 

3. Have all the bacteria been killed in both of these experi- 
ments ? 

4. Does the milk in the two flasks have the same taste? Are 
both samples equally digestible and wholesome ? 

5. Thorough boiling is supposed to kill all the bacteria. This 
is sterilization. 

6. Heating to 160 F. does not kill all the bacteria, but usually 
kills the disease-producing bacteria, or at least a majority of them. 
This process is called Pasteurization. 

7. Do dealers ever add any chemical to milk to keep it from 
souring? Is such substance harmful to those who drink the 
milk? 

8. What are some of the laws and city ordinances concerning 
the purity of milk, its care, mode and time of delivery, etc.? 

9. For discontinuous sterilization, see experiment 4, p. 139. 



BACTERIA. 139 

DISINFECTION. 

Material and Apparatus. — Nutrient gelatin. Milk, one quarter tum- 
bler. Two cubic centimeters of corrosive sublimate solution, one to one 
thousand. Two cubic centimeters of carbolic acid, five per cent. Three 
Petri dishes. 

i. Pour 10 c.c. of gelatin into a Petri dish and add 2 c.c. of 
milk. Keep in conditions favorable to the growth of bacteria. 

2. Prepare as before, but add 2 c.c. of the corrosive sublimate 
solution. Keep in the same conditions as in experiment 1. 

3. Prepare as in experiment 1, but add 2 c.c. of a five per cent 
solution of carbolic acid. Keep in the same conditions as above. 

4. Pour 10 c.c. of gelatin into a Petri dish. Expose to the air 
for three minutes. Heat this dish twice a day (twelve hours apart 
if possible) in a gas oven or over a water bath. Continue several 
days. This is a case of discontinuous sterilization. 

DISEASE-PRODUCING BACTERIA (PATHOGENIC BACTERIA). 

Material and Apparatus. — Slides with mounts of the pathogenic bac- 
teria, such as those producing consumption, typhoid fever, diphtheria, etc. 
Microscope. 

1. Examine the slides under a high power. Use in this con- 
nection the figures and descriptions in books on Bacteria. 

2. Bacteria that do not cause disease are called non-pathogenic 
bacteria. 

3. Explain vaccination. What is immunity? What is anti- 
toxin? In what way is each of the following diseases usually 
acquired : consumption, typhoid fever, scarlet fever, diphtheria, 
smallpox, measles, tetanus, etc.? 

4. Read the history of any of the more notable epidemics of 
typhoid fever. 

5. Are any of these diseases hereditary? 

6. Are malaria and yellow fever due to bacteria? How are 
they acquired? 

7. How do flies and mosquitoes spread diseases? 



140 PHYSIOLOGY. 

ACIDS AND ALKALIES. 

Material. — Weak hydrochloric acid. Weak caustic soda. Red and 
blue litmus paper. Evaporating dish. . 

i. Put a drop of the dilute acid on red and on blue litmus 
paper. What results? 

2. Put a drop of dilute caustic soda on red and on blue litmus 
paper. What results? 

3. Pour a little of the soda into an evaporating dish. Add 
hydrochloric acid, a drop at a time, till the liquid ceases to change 
the color of either the red or blue litmus paper. The liquid is 
now said to be neutral. The process of combining an acid and 
an alkali till the result is neutral is called neutralization. 



APPENDIX. 

Books for the Teacher. — Laboratory Guide in Physiology, Hall, Chi- 
cago Medical Book Company ; Outlines of Practical Physiology, Stirling, 
P. Blakiston, Son & Co. ; Practical Physiology, Foster and Langley, 
The Macmillan Company ; American Text-book of Physiology, Howell, 
W. B. Saunders, Philadelphia; Text-book of Physiology, Hall, Lea 
Brothers, Philadelphia; Human Body (Advanced Course), Martin, 
Henry Holt & Co., New York ; Anatomical Technology, Wilder and 
Gage; Dissection of the Dog, Howell, Henry Holt & Co. ; Dissection 
of the Cat, Gorham and Tower, Charles Scribner's Sons, New York ; 
Human Anatomy, Morris, P. Blakiston, Son & Co. ; Gray's Anatomy, 
Lea Brothers, Philadelphia ; Text-book of Hygiene, Rohe, The E. A. 
Davis Company, Philadelphia ; Hygiene, Coplin and Bevan. 

The teacher should own or have access to one of the three above 
Practical Physiologies, one of the three Descriptive Physiologies, one of 
the guides for dissecting a mammal, one of the large works on human 
anatomy, and one of the larger books on hygiene. 

List of Books for Students 1 Reading. — How to get Strong, Blaikie ; 
Sound Bodies for our Boys and Girls, Blaikie ; Power through Repose, 
Call ; The Technique of Rest, Brackett ; Emergencies, Dulles ; Prompt 
Aid to the Injured, Doty ; First Aid to the Injured, Morton ; Sickness 
and Accidents, Curran ; Bacteria, Prudden ; Dust and its Dangers, 
Prudden ; Drinking Water and Ice Supplies, Prudden ; Ventilation and 
Warming of School Buildings, Morrison ; Pamphlet on Consumption, 
Illinois State Board of Health, Springfield, 111. ; School Sanitation and 
Decoration, Burrage and Bailey, D. C. Heath & Co. ; The Skin and its , 
Troubles, D. Appleton & Co. ; Practical Sanitary and Economic Cook- 
ing, Abel, Public Health Association ; The Temperance Teachings of 
Science, Palmer; The Nature and Effects of Alcohol and Narcotics, 
Luce; Baths and Bathing, D. Appleton & Co. ; Brain-work and Over- 
work, Wood ; Wear and Tear, Mitchell ; The Physiology of the Senses, 
M'Kendrick and Snodgrass ; The Throat and the Voice, Cohen ; 

141 



142 PHYSIOLOGY. 

Handbook of Nursing, State Hospital, New Haven, Conn. ; Text-book 
of Nursing, Weeks-Shaw ; Nursing : its Principles and Practice, 
Hampton ; The Roller Bandage, Hopkins. 

Apparatus, — Part of this can be borrowed from the physical or 
chemical laboratory. Microscope ; dissecting set ; bone forceps ; brass 
syringe ; pinchcock ; retort stand, with clamp and rings ; compasses 
(dividers) ; clamp (bull-dog forceps) ; apparatus for demonstrating the 
action of the heart (Descriptive Physiology, p. 45); galvanized iron 
trays, 18 inches square, 3 inches deep; Bunsen burner; meat saw; 
grindstone ; water bath ; wire window-screen, 3 pieces, each 6 inches 
by 3 inches ; wooden faucets, 8 or 9 inches long ; mortar and pestle ; 
glass tubing, from \ inch to | inch, assorted ; glass slides, 24 ; cover 
glasses, \ inch, 50 ; bell jar with stopper, 1 quart ; thistle tube ; medi- 
cine droppers, 6 ; beakers, 6 assorted ; candy jars, 6 ; evaporating 
dishes, 2 ; graduate, 9 inches high ; lactometer ; pipette, large ; ther- 
mometer, chemical ; thermometer, physician's ; linen tester ; tripod 
magnifier ; watchmaker's glass ; gallon bottle ; rose jar or globe aqua- 
rium, 8 inches in diameter; lamp chimney, common; lamp chimney, 
straight (argand) ; laryngoscope (borrow of physician) ; dentist's mirror ; 
air pump ; bellows, 2 pairs ; bulb syringe ; 15 feet rubber tubing, black, 
pure gum, f inch inside diameter; rubber dam, 6 inches square; 
squawkers, 6 ; rubber coin pad ; scales ; window glass, 3 inches square ; 
small sponges, 2 ; corks, assorted ; rubber stoppers, assorted ; cork 
borer ; filter paper ; glass funnels ; parchment or parchment paper ; 
test-tubes, 48, 4-inch and 6-inch ; test-tube rack ; sheet lead, 8 inches 
long, 1 inch wide ; red electric bell wire, 4 feet ; colored crayons, 
1 box; straw paper, 18x12 inches, 20 pounds; dissecting boards, 
18x12x1 inches, 1 for each 2 students; dissecting boards, 6x8x T 3 B 
inches, 1 for each student; cardboards, 6x4 inches, white, 24; seals 
(legal), 1 inch diameter, red, green, blue, and yellow, 6 of each ; skeins 
of worsted, all colors and shades; white court plaster, 12x6 inches; 
petri dishes, 12; flasks, 12. 

The following apparatus can be gotten at home : cord, red, blue, and 
white; white tissue paper; foot-rule; block, 1 inch square; hammer; 
nails; scantling, 2x4x16 inches; board, 24x8x1 inches; shingle; 
thread ; needles ; tumblers, 3 ; marble ; mosquito netting, 1 foot square ; 
red ink ; blue ink ; file ; tape measure ; crayon ; broom wire, 3 feet ; 
horseradish bottles, 3 ; quart fruit jars, 6 ; picture-cord wire, 1 foot ; 
step-ladder ; ink pad ; plate ; seamless cup or basin ; large spoon ; tiny 



APPENDIX. 143 

spoon ; tin plates, 4 ; patty pans, 6 ; muslin, 1 foot square ; frying pan 
bowl, 1 quart ; pail ; fork ; hand mirror ; darning ball ; child's stocking 
piece of lawn hose, 1 foot ; soap ; 3-gallon crock ; cotton batting 
feather ; 2 pens ; tenpenny nails, 6 ; pins ; pint fruit jars, 6 ; quart 
basins, 3 ; teeth, human, 1 for each student ; spool or cork, 1 inch 
diameter, 1 for each student ; sealing wax, 1 pound (the cheaper kind, 
used for sealing jars). 

Materials. — Chemicals : chloroform, 1 pound ; phosphorus, 1 ounce ; 
lime water, 1 pint ; oxygen (chemical laboratory) ; wax tapers (Christ- 
mas candles), 12 ; sulphuric acid ; carbon dioxid (chemical laboratory) ; 
litmus paper, blue and red ; litmus solution, 1 quart ; hydrochloric 
acid ; ammonia ; potassium nitrate ; ether, | pound ; alcohol, 1 gallon ; 
nitric acid ; caustic soda ; osmic acid, \ ounce ; iodin ; potassium 
iodid ; copper sulphate ; acetic acid ; potassium bichromate ; iodin 
solution (see p. 145) ; Fehling's solution (see p. 145) ; pancreatin, 
10 grams; peptone; rennet, or rennin ; pepsin, 10 grams; olive oil, 
small bottle ; ground flaxseed, half pound ; formol. 

The following materials can be brought from home : salt ; vinegar ; 
chipped beef ; corned beef ; round steak ; potato; milk; bread; apple; 
turnip; eggs; beans; white flour; entire wheat flour; corn meal; 
laundry starch ; cornstarch ; pecans ; raisins ; cane sugar ; beet sugar ; 
maple sugar ; grape sugar ; corn sirup ; maple sirup ; molasses ; 
sorghum ; honey ; candies ; figs ; dates ; fresh fruits ; dried fruits ; 
home-made and " store " jam ; jelly ; lard ; cooking soda ; butter ; 
cream ; onion ; cheese ; compressed yeast ; quinine ; ice. 

The following firms handle chemicals, glassware, and rubber goods : 
The Bausch & Lomb Optical Co., Rochester, N.Y. ; Eimer & Amend, 
New York ; E. H. Sargent & Co., Chicago ; Henry Heil Chemical Com- 
pany, St. Louis. 

Dissecting Material. — In small amounts, this will naturally be ob- 
tained from the local butchers. In larger quantities, it is best to send 
to the larger slaughtering houses, such as Swift & Co. or Armour & 
Co., Union Stock Yards, Chicago. They can supply plucks, eyes, kid- 
neys, etc. Plucks usually cost 25 cents apiece, eyes from 2 to 5 cents 
apiece, not including shipping expenses. This material should be 
thoroughly cooled before being shipped, and in warm weather should 
be well iced during shipment. 

Rabbits can usually be bought in the local markets, and, in many 
places, come at about 15 cents, or two for a quarter. In engaging 



144 PHYSIOLOGY. 

them, bargain that the heads and skins be left on, or else that they be 
skinned on the morning of the day they are to be used. For the dissec- 
tion of the internal organs, of course, they should not be dressed. They 
are often badly "shot up. 1 ' In some places it may be possible to get 
rabbits that have been trapped. 

Frogs can be bought of B. F. McCurdy, 4012 State Street, Chicago; 
the Neuenfeldt frog farm, Oshkosh, Wis. (main store, 114 S. Water St., 
Chicago) ; A. A. Sphung, North Judson, Ind. ; H. H. & C. S. Brimley, 
Raleigh, N.C ; Frye & Ruthven, Morningside College, Sioux City, la ; 
Henry M. Stephens, Carlisle, Pa. If you have difficulty in getting frogs 
or other material, write to the professor of physiology in your State 
University. 

Models. — Manikin, Auzoux papier-mache', made in Paris, $150 to 
$300 and up. Imported by Ward's Natural Science Establishment, 
Rochester, N.Y., or The Kny-Scheerer Co., New York. Separate papier- 
mache' and plaster of Paris models of the head, brain, eye, tongue, 
larynx, limbs, ear, etc., from $2 and $3 up. These are very desirable for 
schools that cannot afford the manikin. Many of the dealers in school 
supplies handle these goods. 

Microscopes. — Microscopes are sold by the Spencer Lens Co., 
Buffalo, N.Y. ; The Bausch & Lomb Optical Co., Rochester, N.Y. ; 
Eimer & Amend, New York; James W. Queen & Co., Philadelphia; 
Williams, Brown & Earle, Philadelphia; The Franklin Educational Co., 
Boston; William Krafft, New York; and by various school supply 
houses. 

Microscopic Slides. — The school should have prepared slides showing 
striated muscle fibers, plain muscle fibers, and sections of spinal cord, 
brain, nerve ganglion, skin, bone, tooth, kidney, tongue, cartilage, 
developing bone, stomach, small intestine (with capillaries injected), 
liver, etc. Such slides are supplied by the dealers in microscopes. 
They will furnish lists and prices on application. 

Dissecting Instruments. — The best sets for the work outlined in this 
book are put up by The Bausch & Lomb Optical Co. and the Spencer 
Lens Co. (addresses above). 



APPENDIX. 145 



FORMULAS. 

IODIN SOLUTION FOR STARCH TEST. 

Dissolve 4 grams of potassium iodid in 40 cc. of distilled water. 
Add 1 gram of iodin. After this is dissolved add water to make 
1000 cc. 

FEHLING'S SOLUTION (HALL). 

Into a half-liter, glass-stoppered bottle put 34.64 grams of copper 
sulphate. Add water to make 500 cc. Label " Fehling's Solution A." 

In a similar bottle put 173 grams of potassic-sodic tartrate (Rochelle 
salts) and 50 grams of caustic soda, weighed in sticks. Add enough 
water to make 500 cc Label " Fehling's Solution B." 

Keep the two solutions separate, mixing in equal amounts when 
desired for use. 

NORMAL SALT SOLUTION. 

Salt 6 grams. 

Water, distilled 1 liter. 

HARDENING LIQUID (FOR BRAIN). 

Potassium bichromate . . . .10 grams. 
Formalin, or formaldehyde . . . 20 cc. 
Water 500 cc. 

LIME WATER. 

Quicklime size of hen's egg. 

Water . 1 quart. 

Pour off clear liquid for use in experiment. 

FORMALIN (FOR PRESERVING SPECIMENS). 

Use Twice as much bulk of liquid as of material to be preserved. 
Formol ....... 1 pound. 

Water . 12 quarts. 



INDEX. 



Absorption, 95. 

And bile, 97. 
Accommodation, 113, 114. 
Acids, 140. 
Adam's apple, 122. 
After-images, 116, 117. 
Air, expired, 53. 
Air currents, 59. 
Albumen, 70, 71. 
Alkalies, 140. 
Anvil, 120. 
Aorta, 23, 24, 26, 32. 

Abdominal, 32. 

Arch of, 32. 

Thoracic, 32. 
Arbor vitas, 101. 
Arch, neural, 127. 
Artery, cardiac, 28. 

Iliac, 33. 

Mesenteric, 32. 

Pulmonary, 24. 

Renal, 67. 

Structure of, 34. 

Subclavian, 32. 
Arteries, 34. 

Distribution of, 32. 

Injection of, 40. 
Atlas, 128. 
Auricles, 24. 
Axis, 128. 
Axis cylinder, 18. 

Bacteria, 135. 

Growth of, 136. 

Non-pathogenic, 139. 

Pathogenic, 139. 
Beefsteak, 70, 77. 
Bicuspids, 85. 
Bile, 81. 

Action of, 94. 

Duct, 81. 

Sac, 81. 
Black-and-blue spot, 64. 



Blindness, color, 117. 
Blind spot, 115. 
Blister, 63. 
Blood, circulation of, 34. 

Color of, 57. 

Frog's, 43. 

Gases in, 57. 

Human, 43. 
Bone, composition of, 131. 

Frontal, 129. 

Hyoid, 123, 124. 

Long, 13. 

Occipital, 129. 

Parietal, 129. 

Shin, 8. 

Structure of, 13, 14, 131. 

Thigh, 8. 
Brain, 98. 

Hardened, 100. 
Bread, 70. 
Bronchus, 23. 
Bulb, spinal, 18, 100. 
Bulla, 118. 

Canalicules, 131. 
Canals, Haversian, 131. 

Semicircular, 121. 
Candle, burning, 55. 
Canine teeth, 85. 
Capillaries, 34. 

Flow in, 35. 
Capsule, urinary, 68. 
Carbohydrates, 69, 73. 
Carbon dioxid, 55. 

In rooms, 60. 
Carpet sweepers, 61, 62. 
Cartilage, 9. 

Arytenoid, 123. 

Costal, 130. 

Cricoid, 122. 

Of ear, 118. 

Intervertebral, 129. 

Thyroid, 122, 124. 



147 



148 



INDEX 



Cartilage of windpipe, 22, 23. 
Caruncle, 106. 
Casein, 69. 
Cavity, neural, 16. 
Cecum, 80. 
Cells, 2, 3. 

Of epidermis, 64, 65. 

Nerve, 19. 
Centrum, 127. 
Cerebellum, 18, 98. 
Cerebrum, 98. 
Chest expansion, 54. 
Choroid coat, no. 
Chyle, 97. 

Receptacle, 97. 
Ciliums, 50. 

Circulation and gravity, 39. 
Clot, 44, 46. 

Clothing, waterproof, 66. 
Coagulation of blood, 44, 45. 

Of egg, 70. 
Coccyx, 128. 
Cochlea, 121. 
Color blindness, 117. 
Column, spinal, 128. 
Combustion, chemistry of, 54. 
Conduction of heat, 66. 
Conjunctiva, 105, 106, 107. 
Convection, 66. 
Convolutions of brain, 17,98. 
Cord, spinal, 15, 99. 

Canal, 19. 

Fissure, 19. 

Horn, dorsal, 19. 
Ventral, 19. 

Matter, gray, 18. 
White, 18. 

Reflex action of, 20. 

Septum, dorsal, 19. 
Cords, tendinous, 27. 

Vocal, 123, 125. 
Cornea, 105, 107. 
Corpus callosum, 101. 
Corpuscles, colored, 35, 43, 44. 

Colorless, 35, 43, 44. 

Of touch, 102. 
Cream, 69. 

Dermis, 64. 
Diaphragm, 79. 



Disinfection, 139. 
Drum skin, 118. 
Duct, thoracic, 97. 
Duodenum, 80. 
Dust, 61. 

Ear, 118. 

External, 118, 

Middle, 119. 
Emulsion, 72, 94. 
Enlargement, cervical, 16. 

Lumbar, 16. 
Epidermis, 64. 
Epiglottis, 87, 122, 125. 
Esophagus, 22, 80, 87, 122. 
Eustachian tubes, 87, 121. 
Evaporation and heat, 66. 
Excretion, 63. 
Eye, Action of, in. 

Dissection of, 107. 

External, 105. 

Images, in, 112. 

Light in, 112. 

Facets, 128. 

Fat in food, 69, 71. 

Globules, 72. 

Pancreatic digestion of, 94. 
Fehling's solution, 73, 145. 
Femur, 8, 13. 
Fermentation, 133. 
Fibrin, 45, 46. 
Flasks, 135. 
Foods, 69. 
Foodstuffs, 69. 
Freckles, 65. 
Fulcrum, 12. 

Ganglion, 17, 40. 
Gases in blood, 57. 
Gelatin, nutrient, 135. 
Glands, infra-orbital, 86. 

Lymphatic, 23. 

Oil, 65. 

Parotid, 85. 

Sublingual, 86. 

Submaxillary, 86. 

Sweat, 64. 
Glottis, 125. 
Gluten, 75. 



INDEX. 



149 



Gristle, 9. 

Gullet, 22, 80, 87, 122. 

Hairs, 64. 

Hammer, of ear, 119. 
Heart, action of, 29. 

Beat, 21. 

Dissection of, 26. 

And lungs, 22. 
Heating and ventilation, 59. 
Hemispheres, 17,98. 
Hilum, 67. 
Humor, aqueous, 108. 

Vitreous, 109. 

Images, in eye, 112. 
Incisors, 84. 
Injection of arteries, 40. 
Intestine, large, 80. 

Model of, 96. 

Small, 80. 
Iodin, 73, 145. 
Iris, 105, 108. 

Jaw movements, 90. 

Joints, ball-and socket, 9, 130. 

Hinge, 9, 130. 
Juice, gastric, 93. 

Pancreatic, 94. 

Kidney, 67, 81. 

Structure of, 68. 
Kneecap, 8, 130. 
Knot, surgeon's, 42.- 

Lacteals, 97. 
Lacunas, 131. 
Lamellas, 131. 
Larynx, 22, 124. 
Lens, crystalline, 108. 

Capsule, 108. 
Levers, 12, 13. 
Ligaments, 8. 

Suspensory, 115. 
Lobes, olfactory, 17, 99. 

Of lung, 23. 
Locomotion by reaction, 14. 
Lung and air pressure, 51. 

Capacity of, 52. 

Dissection of, 22. 



Lung, inflation of, 22, 51. 

Structure of, 25, 49. 
Lymph duct, 97. 

Mater, dura, 17, 98. 

Pia, 99. 
Matter, gray, 18, 101. 

White, 18, 101. 
Meat, cooking of, 77. 
Membrane, mucous, 23, 83, 96, 122. 

Tympanic, 118. 
Mesentery, 80, 82. 
Microscope, 1 (Fig. 1, facing p. 1). 
Milk, 69, 76. 

Digestion of, 93. 

Pasteurization of, 138. 

Sterilization of, 138. 
Mineral matter, 69, 76. 
Molars, 85. 
Mouth, 82. 
Muscle, 4. 

Abdominal, 79. 

Action of, 9. 

Arytenoid, 124. 

Belly of, 7. 

Biceps, 4. 

And bone, 12. 

Crico-arytenoid, 123. 

Crico-thyroid, 123. 

Deltoid, 5. 

Digastric, 86. 

Extensor, 4, 8. 

Of eyeball, 106. 

Fiber, plain, 33. 
Striated, 11. 

Flexor, 4, 8. 

Insertion of, 7. 

Masseter, 6, 86. 

Oblique, inferior, 106. 
Superior, 106. 

Origin of, 4, 7. 

Papillary, 27. 

Pectoral, 5. 

Rectus, 106. 

Sheath, 8. 

Shortening, 10. 

Stapedius, 120. 

Structure, 10, 11. 

Temporal, 6, 86. 

Tensor tympani, 120. 



150 



INDEX. 



Muscle, thyro-arytenoid, 123. 
Triceps, 4. 

Neck, of tooth, 83. 
Nerves, auditory, 99, 121. 

Cranial, 99. 

Facial, 99. 

Glosso-pharyngeal, 100. 

Hypoglossal, 100. 

Optic, 99, 107, 109. 

Sciatic, 7, 9, 17. 

Spinal, 15. 

Vagus, 100. 
Nerve fiber, 18. 

Root, dorsal, 17. 
Ventral, 17. 

Sheath, 18. 
Nervous system, cerebro-spinal, 15. 

Sympathetic, 40. 
Neutralization, 140. 
Nitrogen, 55. 
Nucleus, 43. 

Oil glands, 65. 
Oxygen, 55. 

Palate, hard, 83, 87. 

Soft, 83, 87. 
Pancreas, 80. 
Papillas of tongue, 87, 104. 

Circumvallate, 104. 

Filiform, 104. 

Fungiform, 104. 

Of skin, 64. 
Parchment tubes, 74, 95. 
Pasteurization, 138. 
Patella, 8. 
Peptone, 94. 
Pericardial liquid, 24. 
Pericardium, 24. 
Periosteum, 9. 
Peristaltic motion, 79. 
Peritoneum, 79. 
Perspiration, insensible, 66. 
Petri dishes, 135. 
Pharynx, 83, 87. 
Pigment bodies, 65. 
Plasma, 43, 44. 
Pleura, 22. 



Plexus, brachial, 17. 

Sciatic, 17. 

Solar, 40. 
Potato, 70. 

Cooking of, 78. 
Power, 12. 
Processes, 127. 

Articulating, 128. 

Ciliary, 109. 

Lateral, 128. 

Spinous, 128. 

Transverse, 128. 
Pronation, 130. 
Proteids, 69. 

In intestine, 94. 

In stomach, 93. 

Test of, 71. 
Pulse rate, 21. 
Pupil, 105, 108. 
Putrefaction, 136. 
Pyramid, urinary, 68. 

Radiation of heat, 65. 
Rectum, 81. 
Reflex action, frog, 20. 
Respiration, movements of, 47, 49. 

Rate of, 47. 

Special forms of, 52. 
Retina, no. 
Rice, 70. 

Ring, neural, 127. 
Root of nerve, 17. 

Of tooth, 83. 
Rubbers, effect of, 66. 

Sacrum, 128. 

Saliva, 90, 92. 

Salts, 69. 

Scab, 44. 

Sclerotic coat, 105, 109. 

Sense of hearing, 118. 

Muscular, 103. 

Sight, in. 

Smell, 103, 104. 

Taste, 103, 104. 
Serum, 44, 46. 
Skeleton, 127. 
Skin, 63. 

Structure of, 64. 
Skull, 129. 



INDEX. 



151 



Snail shell, 121. 
Snow, dust in, 61. 
Speech, 125. 
Spleen, 80. 
Starch, 73, 74. 

Digestion in intestine, 94. 
Mouth, 92. 
Sterilization, 138. 

Discontinuous, 138. 
Stirrup, 120. 
Stomach, 80. 
Sugar, 74. 

Grape, 75. 

Milk, 69. 
Supination, 130. 
Sutures, 129. 
Swallowing, 91. 
Sweat glands, 64, 65. 

Pores, 64. 
Synovia, 8, 124. 

Tan, 65. 
Taste, 103. 

Buds, 104. 
Tattooing, 65. 
Teeth, 83. 

Acid on, 84. 

Arrangement, 85, 88. 

Kinds, 84. 

Parts, 83. 

Structure, 84. 
Temperature of body, 58. 

Sense, 103. 
Tendon of Achilles, 7. 

Of diaphragm, 81. 
Thoracic duct, 97. 
Tibia, 8. 

Tissue, connective, 10, 18. 
Tongue, 87. 

Papillas of, 104. 
Touch, 102. 

Corpuscles, 102. 
Trachea, 22. 
Tube, Eustachian, 121. 

Urinary, 68. 
Tympanum, 118. 



Ureter, 67.. 

Uvula, 83. 

Valve, aur-vent, 26. 

Mitral, 28. 

Semilunar, 27. 

Tricuspid, 27. 

In veins, 38. 

Vent-art, 27. 
Veins, 34. 

Cardiac, 26. 

Gastric, 33. 

Hepatic, 33. 

Iliac, 33. 

Innominate, 33. 

Jugular, 33. 

Mesenteric, 33. 

Pancreatic, 33. 

Portal, 33. 

Postcaval, 24, 33. 

Precaval, 24, 33. 

Pulmonary, 25. 

Renal, 67. 

Splenic, 33. 

Subclavian, 33. 

Valves in, 38. 
Ventilation and heating, 59. 
Ventricle, of brain, 100. 

Of heart, left, 24. 
Right, 24. 
Vertebra, 127. 

Cervical, 128. 

Lumbar, 128. 

Thoracic, 128. 
Vestibule, of ear, 120. 
Villuses, 81, 95, 96. 
Voice, 122. 

Waste products in breath, 57. 
Water, in foods, 69, 70. 
Waterproof clothing, 66. 
Weight, 12. 
Window, oval, 120. 

Round, 119. 
Windpipe, 22, 122. 

Yeast, 133, 134. 



IUN 6 V*. 



